However, this claim will not hold up in court or in any law situation anywhere as long as there are rational minds present.
While the people who have tried to use this claim may have actually believed it themselves, its hard to believe someone who has killed someone...allegedly killed someone.
Every instance of a possession has been disproved by science, or really good investigative work. Not one single proven video or photo exist. Maybe there is a reason for that.
You are already labeled as a liar. No one will believe a paranormal event has happened to you, just short of having stigmata happen to you in front of everyone, I think you are on your own.
Check this out... Demon Murder Trial
"On November 24, 1981, in Brookfield, Connecticut, Arnie Cheyenne Johnson was convicted of first-degree manslaughter in the killing of his landlord, Alan BonoSo." -wikipedia
They tried to win the case based on demonic possession, and claims that Arnie was not responsible because of it. The Glatzels, johnsons residence at the time, had many different occurences happen in there home. All noted, and even made it onto a TV show.
And still no one believed.
In short, no matter how you present a case of possession dealing with murder, you will not win, the only reason you have to know is that no one trust you, so no one will believe you. The only thing they think is possessed is your brain.
Good Luck With That Buddy