Guilt Ridden Accomplice

Who I thought was my homie dropped the dime. So I gotta peel his cap with the nine. —Mc Eiht From Compton's Most Wanted.

It's easy to trust your childhood friends, or loyal minions with your secrets but even they have a limit to what they'll keep secret. Perhaps a group of drunken teens ran over a little kid, and decides to close ranks, make a pact, cover everything up and keep the crime to themselves. But one or more group members are uncomfortable with the secret and appears to be cracking under the pressure, and could possibly rat out the other party members that were involved. Whether or not they actually squeal, stay silent, or get killed by their supposed friends varies from movie to movie. Usually when this happens everyone becomes paranoid of one another when it comes to being a potential snitch. This trope is very common in horror/thriller/crime dramas/murder situations.

Overlaps with A House Divided, Murder Is the Best Solution, and sometimes Defector From Decadence. Usually leads to a Plethora of Mistakes.

Examples of Guilt Ridden Accomplice include:

• Violet from Stranger Than Fiction might qualify since she was starting to get panicky and erratic. She either hanged herself or one of her friends (presumably Emma) rubbed her out, and made it seem like a suicide.
• A key part of the Hitchcock movie "Rope"
• Valerie Hawthorne from Ace Attorney.
• David Reynolds from The Liars' Club is starting to doubt his best friend's innocence regarding the rape and murder of a fellow friend. But he's of the "kept silent" variety who continued to destroy evidence with the rest of the group.
• One well known example could possibly be the Comedian from Watchmen. Of course he pays for this with his life. He wound up being the victim of Murder Is the Best Solution variety.
• Cleon from Dead Presidents is of the broke down and squealed variety.
• John Grisham's The Associate has a rare case of a guilt-ridden mastermind. Baxter Tate, accused but never convicted of rape back in college, goes through rehab and decides to patch things up with the woman who accused him. Problem is, it's the evidence of this rape and the possibility of being labeled an accomplice that's being held over protagonist Kyle McAvoy's head by a mysterious conspiracy, and so the conspiracy has Tate killed to keep their leverage.
• Rachel from The Haunting of Sorority Row starts to show signs of this trope.
• The murder victim from the episode of Law & Order: Special Victims Unit that dealt with female-on-male rape turned out to be one of these. She and a couple of friends raped a male stripper at knifepoint during her bachelorette party. Years later she was confronted by her victim and she felt guilty enough to confess her crime and turn over the names of her accomplices. When she told the other women her plans, they killed her to cover up their crime.
• The protagonist of Armored who quickly goes from accomplice to Spanner in the Works when the theives' hideout is found to be not as secluded as they thought and his fried tries to solve the problem by killing the witness, breaking the head organizer's deal with the protagonist that there would be no casualties.
• In Tsukigasa, while Kuroe never approved of thievery the robbers who saved him were surprised when he tried to make off with their maps and Tatsumi was surprised when he gave them to him to help arrest the criminals and Kuroe still wanted to turn himself in too. Ultimately it comes down to Kuroe being a righteous sort of person and wanting to protect Azuma, the criminal's next target.
• Ethel Rogers from And Then There Were None, who mentally collapses when it's revealed that she and her husband Thomas killed their rich spinster boss by with-holding the lady's medicines so she'd die of illness/old age they'd inherit her wealth. And the Serial Killer murders her in her sleep because she was repentant and thus "deserved" to die more peacefully than Mr. Rogers. Who gets beaten to death few later.
• Some cases in Detective Conan have people who were complicit in a crime, and years later feel horrible about it. They're later liable to be the ones confessing everything, but tend to either be killed off by the case's Big Bad to knowing a little too much, or targeted by a Sympathetic Murderer for their part on the crime itself.