Using the comics as an aid to solve the case.
Well this should go without saying because of the title, but comic book spoilers ahead.
I decided to make a quick list of Fables that we now survived into the 2000s decade in the series. The idea is if they survived into the 2000s, they could never have been convicted of the murders in the 1980s. So let's take a quick look at some of the suspects that still survived into the 21st century, and therefor can not be the murder. This of course is under the assumption that the crime is solved, and the murder is punished.
- Ichabod Crane: Survived "the scandal" which presumably is a part of what we are looking at now, where it was confirmed that he "sexually harassed" Snow, and has since been living amongst the mundys. Welling being seduced by Cinderella he stats that the scandal was all "stuff and nonsense". Never the less he betrayed Fabletown and sold it out, and was eventually killed by Bigby, who smashed his head in with a statue of Napoleon.
- Bluebeard. The great schemer and wife killer is alive in well in the 2000s until he is killed off by Prince Charming in a sword duel, partially out of a desire to protect Snow's honor but in reality to have Fabletown take over his considerable wealth to run the government with. A job he soon after wins in the election.
- Jack. Jack the great trickster survives well into the 2000s and beyond. Outright murder isn't in his MO anyways, especially murder that wouldn't involve money. His main love.
- A Mr. Toad. I was told be a poster that indeed a Mr. Toad does officially show up in the books, being one of the causalities of the war with the Adversary. Whether this is the Mr. Toad of the game, or Toad JR having taken his father's place we don't know yet. So theoretically Mr. Toad isn't completely off the impossible list, but still is rather unlikely.
- The Boy Who Cried Wolf, seems to be a favorite of some junior detectives. Unfortunately he is mentioned by Jack to be alive in well living on the 7th floor of the Woodlands during "The March of the Wooden Solders".
- Colin. The little pig who liked living in a straw house would go onto live into the 2000s... and then suffer terribly before becoming a sort of spiritual guide for Snow White.
Characters we've meet who don't appear in the later comics to my knowledge. Please correct me if I'm wrong and I'll change the list.
- The Woodsman. I've heard some people say he appear in the Jack comics, but I haven't read them so I'm not sure.
- The Tweedles. Dee and Dum are no where to be seen in the stories, to my knowledge.
- Grendel. The Beowulf baddie isn't in any of the comics I know about.
- Georgie. Bowler hat wearing Georgie doesn't make an appearance in the series.
- The Crooked Old Man. Whether the fable himself, or a simple code name used by the Tweedles for their employer the Crooked Old Man does not appear.
- Mr Toad. As stated above we know a Mr. Toad dies in the war against the Adversary... we don't know if it's the adult Mr. Toad or Toad JR though. As such I'm placing the name here on the unlikely chance.
If people have more suspects to add or take away because they are in the later stories, give a holler and I or others can look into if they are in the comics or not.