The gun was placed in her car in an effort to frame her.
1. If someone fits another person up, they try to make it seem that that person is responsible for a crime. Mr Stone said inmates who had given evidence were trying to `fit him up' There can never be any legitimate basis for police officers to fit up suspects they `know' to be guilty. = frame see also fit out
{f} equip someone or something with something; make a person who is innocent appear guilty (Slang)