Actress Samantha Morton was convicted of threatening a girl with a knife when she was a teenager - following years of bullying while she was living in a care home.
The Minority Report star spent most of her childhood living in institutions in Nottingham, England.
And Morton, 31, has revealed she was tormented by bullies throughout her youth - and when she finally retaliated it led to a conviction and detention in a youth attendance centre at the age of 14.
The two times Oscar-nominee confronted the bullies and held a knife to an older girl's throat, but was arrested and charged with attempted murder.
She was eventually convicted of a lesser charge of making threats to kill.
Morton says, "I was physically abused and I retaliated. (But) the only person I hurt in the end was myself.
"I didn't touch her - wouldn't have touched her - but the police restrained and then arrested me.
"I was locked in a cell for three days. It was terrible. I just sat there thinking, I don't want this life - I'm not a petty criminal. I'm not a thug. I was so ashamed of myself."
The star believes her 18-week sentence helped steer her away from a life of crime, and in future she hopes to take a break from acting to work with children in care.
Morton was first placed in care as a baby and, after a brief spell living with her father, spent the rest of her youth in a variety of foster and care homes.