A young woman who head-butted and robbed a 14-year-old boy of his bicycle was branded a "street bully" by a judge.
Leicester Crown Court was told the victim and his friends used Facebook to track down the mugger, Shermya Pyatt.
Judge Simon Hammond said they were "seriously smart" to use the social networking site to identify the culprit, before passing the information on to the police.
Pyatt (19), of Tudor Road, Black Friars, in the city, was sentenced to 22 months detention.
She admitted robbing the boy on September 17 last year.
The mugging happened at 8.20pm when the victim was with friends in a car park near Tudor Road and Kate Street.
Pyatt and an unknown male accomplice accosted the boy.
The accomplice grabbed him, knocking him off his £100 mountain bike.
Lynsey Knott, prosecuting said: "The defendant got on the bike and the victim took hold of the handlebars, trying to stop her.
"She head-butted him on his nose and left cheek area, causing him to let go and she rode away.
"The complainant was in immediate pain and it really hurt him."
The boy and his friends heard the accomplice use the defendant's first name, Shermya.
Using that information they located her on Facebook.
The court heard Pyatt had received a reprimand and two police warnings for three assaults in 2006.
In March, 2010, she was prosecuted for possessing an imitation firearm, a BB gun, in Highcross shopping centre and in July, 2010, committed a shoplifting offence.
Judge Simon Hammond said: "People are entitled to go about their lives without people robbing them.
"The bike was probably the victim's most treasured possession. He never got it back."
"This defendant is a street bully. There's a nasty, violent streak in her."
Pyatt, who also admitted failing to answer her bail, was arrested nearly two months ago and been in custody since.
Sally Bamford, mitigating, said: "She has expressed remorse for her actions.
"There are positive aspects to her character and she comes from a good supportive background.
"Her mother is in court to support her.
"The offence must have been extremely unpleasant for the victim, but fortunately there was no lasting injury."