The first killer to be convicted using pioneering dog DNA technology has been given a life sentence for the "vicious" murder of a teenage boy.
Chrisdian Johnson must serve at least 24 years in jail after using his powerfully-built pet Tyson as a weapon to savage 16-year-old Seyi Ogunyemi.
As his slightly-built victim lay helpless on the ground, Johnson stabbed him six times before fleeing the scene covered in blood.
Johnson, 22, was convicted after forensic analysis proved to a billion-to-one certainty that blood found on him and at the scene came from the dangerous animal.
Seyi and his friend Hurui Hiyabu, 17, were set upon by a large group of youths and two dogs in Larkhall Park, south London, last April, the Old Bailey heard.
Prosecutor Brian Altman QC told jurors the case was "unique" because the pets were used as weapons.
One witness described the attackers as "vicious" and said they were acting like a "pack of wild animals".
Johnson, of Wyvil Road, south Lambeth, south London, was found guilty by a jury of Seyi's murder and the attempted murder of his friend - said to have been lucky to survive after he was stabbed nine times.
Judge Christopher Moss told him: "You used two fearsome weapons. The first was your pitbull-cross dog, which I have no doubt you had trained to attack and bring down your prey. The second was the knife with which you stabbed Seyi Ogunyemi to death."
The judge ordered Tyson to be forfeited to the police. It faces being put down.
UK 
