SCP Foundation

It's the late 1950s. Past the Prohibition-era of big business crime, but organized crime still exists. J. Edgar Hoover's been publicly embarrassed. Now the FBI's targeting the Mafia. One particularly diligent FBI agent is Agent Vincent Taglietti. However, he's becoming too much of a problem for made man Johnson Shriver. And he'll do whatever it takes to get rid of Taglietti and keep his operation.
Shriver, being quite the occultist on the side, sells part of (or his entire) his soul in order to kill Taglietti and not be caught. But there's one stipulation - Shriver wants the honors of killing Taglietti himself. The Devil (or whomever he makes the selling to) promises Shriver that Taglietti's death won't be solved by any conventional means. Shriver gloats, then plans out Taglietti's murder. He then visits Taglietti at his residence and shoots the man to death.

The actual skip would be the site of Taglietti's residence. Whenever someone attempts to leave the scene of the crime with a piece of evidence (either to bag or to test), the piece is mysteriously "lost" within 24 hours and returned to the scene of the crime - however, it returns in a "different" way. An example:

• A Colt M1911 (handgun) is taken from the crime scene. It is "returned" as a Smith & Wesson Model 10 (revolver).
• Taglietti's body is placed in the morgue. Next day, the body is in a different place at the scene, and wearing a different outfit. He's also been shot in a different place, too.
• The pictures taken of the crime scene don't look the same when developed.

Another thing is that if there is anyone present at the crime scene or looking at their retrieved evidence for at least 24 hours, they'll mysteriously black out. When they come to, the scene is either different or their evidence has gone back to the scene of the crime. The police are stunned and confused. They call in the Foundation and they cordon off the scene of the crime and permanently block off access to Taglietti's residence. Additionally, because of the anomalous properties nothing at the crime scene wears or ages. Taglietti's body is still fresh. The gun looks brand-new.

The resolution of the "story" behind Taglietti's death would be optional. Shriver, confident of his deal with the Devil, brags about killing Taglietti. Of course, with no evidence to convict, the police nor the FBI can do anything about it. But this talk enrages Taglietti's friend FBI Agent Mark Dawson. Dawson confronts Shriver himself, who confirms his act, and Dawson shoots Shriver in revenge. The FBI covers up Dawson and Shriver by claiming "self-defense". Dawson is, although, fired. This ending doesn't necessarily need to be in the skip, it could be its own standalone tale.

Flash forward. Modern day. A new researcher is intrigued by this skip. It's anomalous effects are well documented but unfortunately not so much the story behind it. This researcher makes it his effort to find out who and why this person (simply called "the corpse" by personnel) died. He goes into archives, files, databases. This researcher slowly puts the pieces together and figures out what happened that day. He knows who Taglietti is. He knows what Shriver did. Shriver, now an old and dying man, has long forgotten his acts in the past. Jail does that to you. But the researcher confronts him about Taglietti. Shriver, regretful of his youthful whimsiness, tells the researcher the story. About the ritual. About the murder. About the years of forgetting. The researcher listens to his story and gets up and turns toward the door. Shriver tells the researcher there is little he can do since he is nearly dead.
The researcher merely replies "I know. Enjoy Hell."

So, concept-wise I'm conflicted. On one hand I kind of like the idea of a murder scene that randomizes itself. On the other hand, this is by no means an un-solvable murder all the time and the definition of 'evidence' is a bit awkward.

For example, what's stopping the entire investigation from just happening inside the house? Evidence is only compromised once it leaves, right? But it can be photographed, documented and analyzed right there if it needs to be. Also, I'm assuming you mean that only crime-related objects, not everything in the house, can't be taken out. This defuses the first half of your alternate ending since a record book or a piece of mail tucked away could be analyzed.

Personally, I'm not a fan of "deal with the devil" things simply because I just prefer skips that are…just there. Deals with eldritch entities inevitably require dedicating detached, clinical tone segments to explaining this. This is simply a personal opinion, and other readers may not share it. That being said, the story feels as big as the skip itself and I would suggest trimming it down so that it can be interwoven smoothly with the draft so that they don't drown out the other or create an uncomfortable shift in tone between article chunks.

However, I think the main thing you should prioritize is the fact that evidence doesn't really need to physically leave a crime scene in order for it to be used to charge someone(so the devil wasn't really telling the truth about it being unsolvable). I like the idea of a randomizing crime scene, but I think it needs to be executed and organized better.