A 19-year-old man found guilty of killing another teenager in Southampton was electronically tagged and under a curfew when he carried out the murder.
Lewis Singleton, 18, was stabbed to death in Obelisk Road in Woolston in the early hours on 31 March 2007.
He was attacked by a gang who had failed to find their intended victim.
Rikki Johnson from Bassett, was serving a two-month sentence in the community for burglary at the time and his curfew meant he should have been at home.
Johnson, of Honeysuckle Road, was found guilty of murder, and another 19-year-old, Sercan Calik, of Burgess Road, Bassett, was convicted of manslaughter at Winchester Crown Court on Thursday.
On Friday, 17-year-old Harvell Mason was cleared of murder and manslaughter after the jury failed to reach a verdict.
He had already been convicted of violent disorder.
A 16-year-old was cleared of all charges against him on Thursday.
Johnson had been electronically tagged after he was convicted of burglary on 19 February, 2007.
His curfew meant he should have been at his home address between 2100 and 0600 GMT.
The tag, worn on a plastic ankle bracelet, is linked to a receiver in the offender's home, which is triggered if the curfew is breached.
The monitoring company reports any curfew breaches to the probation service.
Rikki Johnson had already breached his order once
But the probation service will then have to take action by going through the courts, a process which can take several weeks.
Mr Singleton's family criticised the tagging system.
His mother, Jeanette Singleton, said: "People with a violent record shouldn't be allowed curfew orders and liberty.
"If this had happened, Lewis might have had a chance and still be alive today."
Johnson was being monitored by private security firm G4S, which is contracted by the Ministry of Justice (MOJ).
In a statement, G4S said: "Public protection is at the heart of our operation.
"We take our responsibilities for monitoring people seriously."
A spokeswoman for the MOJ said: "Where the court finds the offender in breach it must either make the order more onerous or revoke the order and re-sentence the offender for the original offence."
She said if an offender "wilfully and persistently" breaches an order he or she could be jailed even if the original offence did not carry a prison sentence.
Hampshire Probation Service said Johnson's community order included supervision, unpaid work and curfew requirement.
A spokeswoman said Johnson breached the order and returned to court for failure to comply with the unpaid work requirement, but he was released into the community again.
She said an internal review into the case was being carried out.
Johnson, Calik, Mason and the 16-year-old, who cannot be named for legal reasons, all pleaded not guilty to murder.
Mr Singleton, from Southampton, had been walking with his friend Craig Smith when they were attacked by a gang.
Mr Smith ran off before Mr Singleton was repeatedly stabbed and kicked by the gang.
He managed to run away and catch up with Mr Smith, but then collapsed at the side of the road.
The prosecution said the gang's intended target had been Mr Smith, whom they accused of being racist.
But when they failed to catch him they attacked Mr Singleton instead.
He died the next day. A post-mortem examination revealed he had suffered five stab wounds, one 8.5cm (3.3in) deep, and a traumatic brain injury.