I found this story on Futility Closet's blog here.
"In 1897, testimony from a ghost helped to convict a murderer. Zona Heaster Shue’s death was presumed to be natural until her mother claimed that her ghost had visited her on four successive nights and described how she had been murdered by her husband, Edward. When Zona’s body was exhumed, her neck was found broken, and a jury convicted Edward of murder.
"That may be the last U.S. case of 'spectral evidence,' but it’s not the first. During the Salem witch trials, if a witness testified that 'Goody Proctor bit, pinched, and almost choked me' in a vision or dream, this would be accepted as evidence even if Proctor was known to have been elsewhere at the time.
"'Justice has nothing to do with what goes on in a courtroom,' wrote Clarence Darrow. 'Justice is what comes out of a courtroom.'"