Killer Chrisdian Johnson convicted using DNA from dog

Gang member set bull terrier on victim before stabbing him to death

A gang member who used a dangerous bull terrier to attack a rival before stabbing him to death yesterday became the first person be be convicted using DNA evidence taken from the crime scene and matched to his dog.

Chrisdian Johnson, 22, killed Oluwaseyi "Seyi" Ogunyemi, 16, by setting his dog Tyson on him before stabbing him six times as he wrestled with the animal on the floor.

During the melee Tyson was stabbed twice, and as Johnson fled with his pet, the dog left a 600-yard trail of blood. Officers arrested Johnson 13 minutes after the attack, as he walked bare-chested and covered in blood down a busy south London high street. Tests showed that most of the blood had come from his victim, but that some of it was from his dog.

The police managed to prove that Tyson was the dog used to maul Seyi by taking a DNA sample from the dog and matching it to blood found at the crime scene and on Johnson. It is the first time that dog DNA has been presented as evidence in a British court, and its use has being hailed as a breakthrough in the fight against the problem of aggressive dogs being used by gang members as weapons.

Detective Chief Inspector Mick Norman, who led the investigation, said: "The advances in dog DNA and forensic work now means that anyone who owns a dog and uses it to attack people can be identified and prosecuted."

During the trial at the Old Bailey, the jury heard that Seyi was killed in an apparently gang-related feud in Wandsworth, south London, in April last year. He was with a friend in Larkhall Park when he was attacked by a group of between 15 and 20 youths at about 8pm. Seyi tried to flee over a fence, but was pursued by a dog, dragged to the ground and then stabbed by Johnson.

The victim's 17-year-old friend Hurui Hiyabu was stabbed nine times, but survived. Johnson, of Wyvil Road, south Lambeth, was yesterday found guilty of murder and attempted murder.

Johnson's brother Shane Johnson, 20, of the same address, was cleared of both charges. A third defendant, 18-year-old Darcy Menezes, of Studley Road, Clapham, south London, was cleared earlier in the trial. The other youths involved in the attack have never been identified.

Following the verdicts, Det Ch Insp Norman said that Seyi, who suffered from Crohn's disease and weighed just 7st, "didn't stand a chance".

He added: "This horrific attack was committed on a very slight teenage boy who stood no chance of defending himself," he said. "The fact that Chrisdian Johnson also ordered dogs to take part in the attack illustrates his sickening attitude to violence. When you mix a dog and knives you have a really lethal combination – as in this case."

Police confirmed that Chrisdian Johnson had previously been given a specific exemption by a court to keep Tyson even though it was a dangerous dog by breed. He agreed to have him chipped, tattooed and insured, but further conditions meant the animal should have been kept on a lead and muzzled at all times in public. Officers will apply to have the dog destroyed.

Kit Malthouse, London's deputy mayor for policing, said: "Weapon dogs are an horrific feature of modern Britain. It is important that anyone using a dog as a weapon should feel the full force of the law. As this case has shown, these animals can be as deadly as a knife or a gun, yet paradoxically harder to control. They often terrorise whole neighbourhoods, inflicting injury and tragically, with this case, can even be used as a weapon to kill people."

Johnson will be sentenced at the Old Bailey today.