In trial, Fromme pleaded not guilty to the “attempted assassination of a president” charge, arguing that although her gun contained bullets, it had not been cocked, and therefore she had not actually intended to shoot the president. She was convicted, sentenced to life in prison, and sent to the Alderson Federal Correctional Institution in West Virginia.

Fromme remained a dedicated disciple of Charles Manson and in December 1987 escaped from Alderson Prison after she heard that Manson, also imprisoned, had cancer. After 40 hours roaming the rugged West Virginia hills, she was caught on Christmas Day, about two miles from the prison. Five years were added to her life sentence for the escape. She released on parole in August, 2009, after serving nearly 34 years.