Solving the case with Knox's Decalogue
Judging by chapter 1, this story certainly appears to be a mystery, and many readers seem to think it's a solvable one. If this story is indeed solvable by us, then I submit that it must follow Knox's Decalogue of fair play detective stories. With these commandments, the reader is free from unfair tricks and twists.
For those unfamiliar with the rules, I shall post a modern interpretation of them.
The Knox Decalogue: Umineko version
Knox's 1st: It is forbidden for the culprit to be anyone not mentioned in the early part of the story. (someone from part 1 is the killer. Doesn't need to have a speaking part, and it may even just be part of the background info cards, but we have definitely seen him by now in some form)
Knox's 2nd: It is forbidden for supernatural agencies to be employed as a detective technique. (While this world is undeniably magical there is still no 'I win' button by asking, for instance, a magic mirror to show the location, or identity, of the murderer. The detective, and the detective alone, will solve the case.)
Knox's 3rd: It is forbidden for hidden passages to exist. (no impossible crimes where the only solution is to have the killer pop through a wall wall or teleport into a closed room, also called a locked room mystery, and then sneak away with no traces left behind. Yes, there is magic but that magic is not going to bypass logic, when investigating. All tricks will be discovered during the course of the investigation)
Knox's 4th: It is forbidden for unknown drugs or hard to understand scientific devices to be used. (people can't be killed with some method that is impossible to the reader's viewpoint. Proper explanations are needed for all esoteric murder methods before the case can be resolved)
Knox's 5th: It is forbidden for stereotypical minorities to assist or hinder the detective beyond providing their own conclusions and interpretations, or for said minorities to be the culprit. (having some random butler, or some stereotyped minority, do it is boring and cliché. The killer needs motivation, a history, a background that MUST be exposed in some manner before the reveal)
Knox's 6th: It is forbidden for accident or intuition to be employed as a detective technique. (Bigby isn't going to solve the case by some lucky happenstance or by following a vision from heaven because that would mean he would have access to information that the reader does not, and CAN not, possess. Logic alone must be the key)
Knox's 7th: It is forbidden for the detective to be the culprit. (For Bigby to be the killer, it means he is hiding things from the audience, and therefore is not solvable in a fair way. It goes against everything Knox stands for)
Knox's 8th: It is forbidden for the case to be resolved with clues that are not presented. (a mystery must, MUST, be solvable by the reader before the true culprit is caught)
Knox's 9th: It is permitted for observers to let their own conclusions and interpretations be heard. (remember kids, everyone lies. If someone says they have an airtight alibi, that's probably a lie too. If you are told someone is dead without seeing it with your own eyes, there is a good chance they are alive instead. Trusting people is for saps, every person you meet is likely there to deceive you. There is only two things you can believe in. That is the evidence and the detective)
Knox's 10th: It is forbidden for a character to disguise themselves as another without any clues. (the killer can't disguise himself as, say, an innocent cab driver without leaving a clue to his true identity)
Does this game follow the rules? I do not know. Certainly, looking from episode 1, it appears to follow the rules. We've had 3 investigations so far. All have had clues splattered around the area so that the detective could make some conclusions. There is some problems with the death of Faith's husband, such as the gun issue but I think that was a slip up, not intentional by design.
Therefore...
To all new readers: While it is not conclusive that TellTale is following the Decalogue, there is sufficient evidence, for now, for it to be possible, perhaps probable. Therefore, all theories posted here should do one of two things, either prove one of the commandments has been broken in such a way that it proves that this is not a fair play detective story or craft a theory that doesn't conflict with them. There are plenty of threads where one can create devil's proof arguments. This is not one of them.
Thank you.
Comments
But, Faith's husband is not dead.
eeee whats knox?
I have the same question. :P
5 seconds of Googling returns...
These are the rules that were created back in the early 20th century as a guide for any aspiring mystery writer that wanted to create a fair play whodunit. This style is basically a mystery that is solvable by the reader BEFORE the culprit is revealed by the detective. Ideally, the reader would be able to go back on a reread and be able to see the story in a new light and see it as the culprit being obvious, now that the facts have been revealed.
Here is a TV tropes listing of various stories of that type:
http://tvtropes.org/pmwiki/pmwiki.php/Main/FairPlayWhodunnit?from=Main.FairPlayWhodunit
Some popular examples. Agatha Christie, who wrote many novels during the golden age of detective stories, typically followed it. J.K. Rowling's Harry Potter books were also quite fair. Such as leaving many clues as to who was the one that opened the Chamber of Secrets. Her leaving clues all the time got the readers to search the story so carefully that when the letter from R.A.B. was discovered, the writer's identity was spotted pretty much immediately. Also, all Encyclopedia Brown mysteries are deliberately like this... even if some of the "solutions" are less plausible than others.
On the other hand, Sherlock Homes stories do not tend to be strictly fair since we are not normally looking at the story through the eyes of the detective. Watson does not generally give us the information needed to solve various mysteries before Homes does.
The rules of Knox are not a be all, end all, but if TellTale is playing fair with us readers and is honestly allowing us the opportunity to figure out the culprit before the story ends, then it follows some variation and we can call upon Knox to help us weed out idle speculations that don't go anywhere.
Speculations like
Stuff like that, this is a tool one can use to weed out the more idle speculations and to prevent yourself from getting caught up with endless "what ifs".
I knew the Knox rules.
The biggest question is: did TT followed them? Or they were scared someone can solve the game before the 5th episode?
Puzzlebox, or someone else, can you reassure us that the rules are observed and that we're not wasting our times trying to solve an unfair game?
Thanks.
If you choose to visit Mr Toad first, or don't prevent Lawrence shooting himself again, then Lawrence dies.
I definitely respect the attempt to use these fair-play whodunnit rules as a tool for reaching conclusions about the killer and avoiding endless speculation... But I have to say, I'm skeptical that Telltale will go this route. Murder-mystery appreciators are incredibly savvy these days; chances are that many have seen these fair-play rules at work before and know what possibilities to consider.
A trend I see with most media today, (such as Game of Thrones, Walking Dead, etc) is an interest in surprising the modern consumer in every way they can. Based on the events of Episode 1 I feel that TWAU is, more than anything, trying to accomplish the same. It can most effectively do that if nothing is off-limits. For that reason I suspect Telltale is working on a jaw-dropping, completely unexpected ending that nobody sees coming, though I could certainly be wrong in thinking that.
I appreciate fair-play whodunnits and anything-goes mysteries equally, myself. The Moonstone, one of my favourite novels, is one of the latter... And also one of the most respected titles in the mystery genre. I'm fine no matter which way TWAU chooses to go, but given its current reliance on shock value and plenty of magic in its gameworld, I really do expect a fat, unpredictable twist ending.
Also, if #10 really specifies "characters" rather than "the killer", doesn't the idea of glamour kind of violate that rule?
Interesting question.
It's clear that a glamour is an effective disguise. In theory, yes, you should be able to use them to pretend you are someone else. Either by impersonating someone the players have met or by creating a completely false identity. Even so, the use of a body double disguise is not considered unfair, per say. It's specifically that you can't use a disguise without CLUES.
I could be wrong on the limitations of this ability, so if someone with more knowledge of the source material wishes to rebut me on my assumption, then they should feel free.
It's impossible to say if TellTale is giving us a fair play whodunit at this early stage, with absolute certainty. However, looking over the episode, everything says this is EXACTLY what they are doing. We are given 3 crimes where we can figure out basically what happened by searching the area. There is an issue with the likely murder weapon not having been used recently in the third but that could be a glitch on their part due to story branching. Other then that one aspect, it all fits.
We are even given a suspect that was in the background, never really talked, and whose name we weren't told. Yet, through carefully looking over the episode, we can determine him to be the most suspicious person of the entire story, thus far. Why would TellTale allow us these clues if they were not making a fair play whodunit? Anyone could have made the connection if they had spent some time really going over the story. To think otherwise, is really a bit insulting to the creators of the game. Even I noticed that guy as being suspicious. I just never bothered really trying to spot every place he showed up.
With episodes being 1-2 months apart, there is no way TellTale didn't expect us to find the connection. Why allow us to do this, if it's not a fair play whodunit?
Even if this isn't the case, even if all the clues are simply a massive troll on the players, what is the alternative, assuming you don't want to give up? Everyone is trying to figure out the killer. We are assuming this case is solvable. This is only possible if it's a fair play whodunit. If you wish to solve the case, and truly believe that doing so is possible, then learning about the Decalogue and knowing what sort of theories are not really likely, is critical.
That is why it is important for all would be sleuths to know about Knox and to use his Decalogue to aid their efforts.
Otherwise, you will just be running in circles spitting out Devil's Proof theories, which have no place in a fair play whodunit mystery.
6 is out of the question when it comes to Bigby's intuition mixed with knowledge. We have to think similarly to Bigby to solve the case according to everything else in the Decalogue. A lot of people in doing so miss the chance to solve logically what went on at Lawrence's house.
First off, that case has the suspected culprit say exactly what probably happened when Bigby catches him. Secondly, we have Lawrence confess to trying to suicide, if you go to his place first. Thirdly, we can even see him kill himself if things go badly.
However, both the former points rely on characters telling you things, which is not to be trusted, as per Knox's 9th. That is a down point. Although the third remains valid. Especially when you compare Tweedle's version of events, that Lawrence killed himself upon hearing that Faith was dead, and actually witnessing him kill himself if you tell him his wife is dead.
Even without that though, there is still a great deal of physical evidence in the room itself which can be investigated, as long as you don't uncover Tweedle Dum first.
One item that is problematical though, is the gun. The gun is said to have not been used for quite awhile, however, if Lawrence used it to kill himself, it should have been fired recently. So there is a contradiction. This is acknowledged by myself but will be ignored, at this time, because of the fact that it appears to be a slip up on TellTale's part. It seems TellTale used the same information on the gun for both versions of the murder scene, rather then making sure the differences were there so that people that failed to save Lawerence would also be able to figure out that he killed himself. Whether or not this viewpoint is correct will be revealed when Lawrence's murder is solved.
That said, it is a valid tactic to replay the game, and take other options in it in order to piece together the mystery and this point is mute for anyone that saved Lawrence from killing himself.
Regardless, I fail to see what any of this has to do with Knox's 6th. Bigby never figured out who killed Lawrence in the first place, and all the evidence he found was also shown to the player. The murderer of Lawerence has not been uncovered yet and, as long as the case is unsolved, there is no possibility that this rule has been broken.
It's the red haired guy. The red haired guy with the greenish jacket Bigby and Snow run into on the way to the steps. Mark my words. Unassuming, seemingly unrelated coincidental passing by. He was the killer and wanted to see his public's reaction, if only the worry - lest he be caught early.
I would argue that the two clues you listed are conditional. If we suppose that the killer appears in the game in both his true and glamoured form, he could still avoid giving away clues as to his true identity by remaining silent and having mild enough "tells" on his glamoured form that they wouldn't necessarily give him away, (ie. not arm wounds or milky irises).
And glamoured individuals who are introduced to the player in this form give no clues as to their true identity simply because we haven't encountered that true identity yet, and know nothing of its nature.
In the example you gave, you spoke of the red-headed stranger disguising himself as the cabby. That example features obvious clues; hair colour, distinctive hairstyle (with the curl in the back), etc. That's a fair-play disguise. He isn't shapeshifting when he masquerades as the cabby... He's just dressing up, and is fundamentally relatable to his crook-tied self. Glamour can make a being look entirely different, to the point where you could see a fable and its glamoured form in separate scenes and still have no chance of tying them together
I don't believe that successfully solving a few crime scenes in Episode 1 has any bearing on whether the overarching story follows the 10 tenets or not. Solving crime scenes is a staple of all games in which you play a detective, and those games still maintain the potential to be fair-play or anything-goes when it comes to the full scope of the narrative.
I agree, the red-headed guy is suspicious. But the killer? Not necessarily. He could simply be the errand boy of the true killer, or of an entire host of conspirators. The tenets put forward by Knox seem to apply almost universally to the actions of the detective and the story's main antagonist, so if the red-headed guy is an important lead rather than the killer, it still makes total sense for Telltale to draw attention to him while making TWAU an anything-goes mystery.
I'd say a fair-play whodunnit must adhere to all the rules you give at all times to be worthy of the label. If even one is violated at any time, even if every petty crime or puzzle leading up to the final revelation can be solved beforehand through analysis by perceptive players, the narrative can still be anything-goes even if it's only the conclusion that is a total blindside. That's why it's hard to convincingly bet on TWAU being fair-play at this stage when only one episode has dropped so far; its current pattern of everything being solvable (which I wouldn't say is entirely consistent so far) could be bucked at any time.
And, as I continue to believe, I think the concept of glamour alone breaks one of those rules straight off.
Faith is a killer.
I think he is connected but he is not the killer
About the gun... My memory could be fuzzy, but on my playthrough I wasn't able to save Lawrence, and I'm pretty sure it was explained somewhere that Lawrence shot himself a week or two ago, and slit his wrists as well if I remember correctly. Or even longer, perhaps.
This was after he learned where (or whom) Faith fled to, after leaving him. Whoever it was she went to, I think he feared for her and blamed himself for not being able to provide, etc. Being a fable, it just took him that long to die. That's why the whole place stinks so much, and why the gun wasn't fired "recently" - after all, it was a while ago. As we know, Fables are tough. But it was a while ago and I wrote a whole thesis since then, so memory could be cloudy.
You are also forgetting that only Bigby, Snow, Crane, and the killer know about Faith's death. How on earth would Tweedle Dee know Faith is dead. Most likely by working for the killer to cover up evidence.
Maybe he'll align himself with the cop shown for episode 3? He could just be gathering evidence to "snitch" Bigby out to her.
I think you are misunderstanding the point of this thread, Retneug. While it is not conclusive that TellTale is following the Decalogue, there is sufficient evidence, for now, for it to be possible, perhaps probable. Therefore, all theories posted here should do one of two things, either prove one of the commandments has been broken or craft a theory that doesn't conflict with them. There are plenty of threads where one can create devil's proof arguments. This is not one of them.
If you do not have any further evidence that one of Knox's Rules is being broken, please try and work under the assumption that it is.
Exactly correct. The issue is that the gun should have been fired recently if Lawrence did end up killing himself before your arrival. The fact that it does not say this implies that he either did not kill himself or that TellTale messed up and accidently kept the same information for both versions of the crime scene. The answer should be revealed in chapter two.
The question of how the Tweedles know about Faith's death must be answered. Assuming this is a fair play mystery, then one would guess that the Tweedles were informed by someone that has been mentioned in the story already. It is also emmently reasonable to assume that they were informed by someone that we know or suspect to have been at the crime scene, rather then it being a random passerby.
This is an excellent theory. I would like very much for it to be correct.
If Faith is the killer, that means the severed head is a fake. A fake that is so realistic that one is unable to distinguish it from the real thing. This breaks Knox's 10th and is therefore not permitted.
The role of the red head needs further investigation. He could be the culprit, an accomplice or have an entirely separate agenda.
I understand perfectly well what the point of this thread is. When I initially posted, I questioned the viability of relying on Knox's laws to reach a sound conclusion (which is quite related to the topic, even if I don't embrace the usage of the laws themselves) , and began to make a case for the 10th rule being invalidated by glamour. Everything I posted beyond that were simply rebuttals to your own statements.
As for providing evidence for the 10th being explicitly broken, I am of course incapable of doing that... Because if both a fable and his glamoured form have shown up in Episode 1 without any clues as to their connection, it would be impossible to prove because the situation is defined by an utter lack of evidence. The revelation of this could only come out through witnessing the transformation or the fable's own admission, which of course don't constitute clues... Hence why I tried to argue for this potentially being the case in Episode 1; because if it were happening, we would have no knowledge of it yet.
In suggesting that the red-headed man could be an accomplice rather than the killer, I was trying to show how the attention being drawn to him wasn't necessarily evidence of the narrative being fair-play; I wasn't trying to invalidate one of the rules.
If I were trying to do that in earnest, I'd simply bring up Knox's 2nd and the fact that it's explicitly broken in the first episode. Just because your interpretation of the rule necessitates that the detective must use supernatural means to somehow identify the murderer for it to be broken does not make it so.
The law states; "Supernatural agencies can not be employed as a detective technique". Detective techniques are, as one would guess, techniques employed by the detective to bring him closer to resolution of the investigation... At any point in the investigation. Therefore, by relying on the magic mirror to provide new leads for his case, Bigby employs it as a detective technique and nullifies the rule.
I rather think that by simply making that statement, that you are actually trying to do so in earnest.
Sigh
Very well. Since the point has been raised, we may as well examine it.
This isn't a new argument. The mirror is an acceptable tool, as long as it doesn't show something that is impossible to verify by mundane means (without having used the mirror first, naturally). Since you are interested in this rule, lets me discuss it more in depth.
This variation on the rule does not explicitly state that the supernatural is not allowed in the story. No, there is certainly room for the existence of magic. If there was not, then Knox's second would be completely useless and my foundation for using Knox's Decalogue would fall apart. This is precisely why I use the Umineko variation instead of the original, because the original version outright forbids any form of magic or the supernatural in a proper fair play detective story.
Rather than serving as a tool to solve a mystery by eliminating possibilities that could not be eliminated by any other means, Knox’s 2nd simply serves the purpose of stopping the detective of using the knowledge or level of truth he does not and can not find out himself at this point in time. (you can think of it as a spoiler)
By putting these restrictions it destroys any easy sure-win methods. It makes the game fairer where truth can only be achieved by putting the pieces together using clues and hints provided by the mystery. One most reasonable commandment that only applies to the detective of the story.
Bigby will find Snow's body through his senses, mainly his sense of smell. The game is canon to the comics and vice versa as stated by Telltale and the author of the comics. In the comics it is clearly stated that Bigby knows where Snow is at all times.
It doesn't really break that rule, though. Not if the head was a fake disguised with glamour, which is an element that is explained and emphasized quite strongly in the story.
Really? Huh. That's interesting. So, basically,
That said, Knox's 6th: It is forbidden for accident or intuition to be employed as a detective technique, doesn't necessarily apply to this.
Simply put, Knox's 6th means that Bigby can’t simply know something. Using Bigby's heightened sense of smell is just an alternative means of gaining a physical clue, just like the suspect leaving fingerprints behind is a clue. There is no reason for it to not count, in helping you resolve the case. Also, finding the body is not the same as finding out who killed the person. There can be a hundred reasons that lead to the recovery of a body, none of which need to have anything to do with the detective. Luck is less relevant in this case.
Even so, I'd rather not get into a discussion of something that might happen. If it does, the issue could be revisited then.
As I have said before, the use of glamour is permitted under Knox's rules and should be looked out for. However, if a glamor can effectively conceal someone as another person with NO CLUES whatsoever, then that would break Knox's 10th. There simply must be hints that the head is not what it seems to be. If you can't trust that severed head to be Faith's, and everyone in episode 1 has specifically stated that it is... Then you can't trust anything and you are just going around in circles.
This thread rejects all such Devil's Proof arguments. It's nothing better then random guesses. Therefore, the theory that Faith is the culprit is rejected because it breaks Knox's 10th.
Theory : dead girl is not Faith.
Proves : magic hide Faith from Magic Mirror. Ring was placed in her head that leads to name Faith. But the only prove that dead girl is a Faith is photo in Book of Fables that doesn`t look quite similar and anyway could be changed by someone in advance.
<smiles> Taking my format, I see. I appreciate that.
Hmm. Interesting. I'm impressed by this level of deviousness. If all these suppositions are true then you have beaten Knox's 10th. If we have never met the real Faith then a disguise isn't needed. At least, that's how I see it.
Congratulations, I honestly did not think that was possible. Your theory is ridiculously complex but that doesn't mean it is not Knox compliant...
Okay lets look at the new idea.
Sorry Obi, a hole has been pointed out in your theory.
Thanks to Deathwish47 for catching the problem with this theory!
Some comments :
1) Tweedles may be not misinformed. They showed up in Lawrence place, but we don
t know what they are searching for. Somehow Faith, fakeFaith and Woody are involved in some stuff (in trailer Woody answers question "who else have been involved" answers "a girl with a coat"). When Tweedle enters bars he starts to say "give 100 for information about girl named..." and he didnt finish. So maybe this name wasn`t Faith.2) The entry at achievements area is ofcourse the strongest evidence against my theory. But this information have been added through game and all information can be true, the picture can be misleading due to ingame information gathering...
I would be really disappointed if Faith was not dead and also somehow involved in this, because it would be way too similar to a case in the comics.
Certainly, I'm trying in earnest now. What else am I supposed to do when you politely invite me to either post a theory that abides by your rules, provide evidence that invalidates one of them, or get out?
I, too, am following the Umineko variation of the rules, as my last post will attest. The original list is hardly serviceable, seeing as it excludes "chinamen" from so much as existing in a fair-play whodunnit.
The Umineko version of rule #2 explicitly states; "It is forbidden for supernatural agencies to be employed as a detective technique". It doesn't say "It's totally cool as long as the same information could be arrived at through mundane means". Regardless of whether Bigby could gather the information he acquired from the mirror elsewhere, he chooses to rely on the supernatural instead, and it helps with his investigative process.
When he sees the state of Faith's father, he even says; "Well, I guess we can cross him off the suspect list." That's proof positive that it Bigby utilised the information provided by the mirror as a detective technique to limit the number of potential suspects.
Your assertion that this information could have been gathered elsewhere is pure conjecture, especially considering Bigby had just finished reading Donkeyskin's fable, (seemingly the end-all and be-all of recorded information about fables in Fabletown) and it made no mention of her father's death.
I agree that there is room for the existence of magic in a fair-play whodunnit, so long as it is peripheral to the detective's investigative techniques; essentially, so long as he isn't aided by it in his pursuit of the case's resolution. But as I've just explained, he is. So I would argue that the rule is violated in Episode 1.
I wasn't arguing that Faith was secretely the murderer, but that it perfectly possible for "Faith's head" to be something else through the use of glamour.
We know Faith is in some trouble she can't talk about, possibly through the use of magic (her lips are sealed). The mirror's lips are also sealed, but we know the mirror is capable of showing us dead people because it had no problem showing us her father. We had also seen her corpse, so there isn't a particular reason from a storytelling perspective to hide it from us, so I suspect shenanigans
On the crime scene we found Faith's ribbon with her ring tied to it. Considering Faith's ribbon was located roughly at the same point where the killing blow would have landed, it was surprisinlgy bloodless and undamaged. I also don't recall her wearing that ring. Also notable, her purse can be found on a trash bin, though Bigby doesn't comment on it for some reason.
My guess: Faith faked her death, using a glamour potion on another person. She, or someone helping her, positioned the head in a highly visible place. The second head was placed to shift the focus of the investigation away from her. If there is a serial killer on the loose, Bigby can't dedicate the investigation solely on her, he will have bigger problem to worry about.
EDIT: Isn't Faith's skirt roughly the same tone as the piece of jeans found on the crime scene?
EDIT 2: Alternatively, maybe we haven't met the real killer yet. I know you'll bring up Knox's 1st but bear with me, this is a 5 part series, we're only on episode 1. How late into the story is this rule invalidated? I'de say 2/5ths into the story is fair enough, especially considering that we're going to meet new characters on every episode, if the Book of Fables entries are anything to go by. Hell, there's characters mentioned in this episode we still haven't met and have no clue as to what their identity might be, like the pimp, or "Georgie".
I'm going to bring an example from Phoenix Wright: Ace Attorney, so if you haven't played that game, spoilers. Anyway, in case 1-3, when starting the investigation you are informed that only the victim, the accused and one other person were present in the scene. It is not until the second day of the investigation, after the end of the first trial, that you find out there actually was another group of people present in the scene on the day of the crime, among which the real killer was hiding. This must be about 1/3rd of the way into that particular case, does this example break Knox's 1st? Or is this case compliant with it?
Having the mirror to ascertain whether or not Faith's Father is alive absolutely is peripheral to the investigation. This is made clear by witnessing what happened after Faith's identity was revealed. When that happened, her identity was opened up on a registry roster and she was given a stamp on it that marked her as being deceased.
This is clearly standard procedure, which means that every Fable that dies gets a similar marking. If Faith was in the book then, logically, her father was as well (since it's cannon that all Fables have entries in the archives). Yet, when the mirror revealed that her father was dead, the book was not opened to mark that down on his entry. It is logical to assume that he was already marked down, as he's been dead for quite some time.
Therefore,
Having the mirror show his corpse was simply a more dynamic method of showing his death, as opposed to having his status being shown in the book. It offered nothing that could not be discovered in a similar amount of time, since there is a book right in the room that lists every single Fable and their living status.
To be honest, I think the biggest problem isn't the entry, which is meta knowledge and, therefore, goes against Knox's 2nd. Don't worry about going against meta stuff here. In fact, your willingness to ignore that entry does you credit, I think. No, the biggest problem is the fact that there are zero clues to backup your guess. You have managed to craft a theory that fits into Knox, and I applaud you for your devious thinking, but everything you stated is still pure conjecture.
Without clues that can show that your theory is right, then there is no realistic way for the case to be solved without Devil's Proof arguments. It's possible to get proof in later episodes still, but until you find some, there is always the specter of you being hit with Knox's 8th: It is forbidden for the case to be resolved with clues that are not presented.
Did you get your idea from a case in the comics as Grad Black Heart mentioned? His post leads me to give your idea more credibility then I initially did and I wouldn't mind hearing the exact circumstances of that plot twist.
If the mirror's information was used by the detective to rule out Faith's father as a suspect, it is pertinent to the investigation. Period.
I'm not concerned with whether Bigby could have acquired that information another way. As I said in my last post:
"The Umineko version of rule #2 explicitly states; "It is forbidden for supernatural agencies to be employed as a detective technique". It doesn't say "It's totally cool as long as the same information could be arrived at through mundane means". Regardless of whether Bigby could gather the information he acquired from the mirror elsewhere, he chooses to rely on the supernatural instead, and it helps with his investigative process."
It's a fact that Bigby relies on the mirror as an investigative technique. It's a fact that ruling out suspects is inexorably tied to pursuing the resolution of the case. Therefore, the detective relies on the supernatural to make progress in his case, which invalidates Knox's 2nd.
Rebuttal: All of the pictures in Faith and the prince's house clearly show (the dead) faith is faith...
Now that you mention it, Toad said he had borrowed the donkey skin coat from a girl, yet when you arrive for the first place he says he wasn't aware that Woody had company. We have no evidence that Faith has ever been in that apartment before, we even have evidence against it! The reason Woody starting beting her up is because she said she didn't recognise him. If she had visited him before, she would know him!
So when, and how, did toad borrow that coat?!
There's definitely some shenanigans going on...