After Billy Milligan was found not guilty by reason of insanity, he was sent to a mental institution in Ohio. However, he managed to escape several years later and was apprehended in Florida. He was then transported back to Ohio and was admitted into a mental hospital, yet again.
Billy Milligan was released back into society in 1988 after a psychiatrist confirmed that he was no longer a threat to the public. He lived a quiet life after that and died of cancer at 59 years old.