NEW USE OF DNA EXPERT EVIDENCE DOGS CRIMINALS
Innovative use of DNA profiling has unlocked the door for a forensic zoologist to help track down wrongdoers through evidence left by dogs.
In the first case of its kind, dog DNA was used to convict 22 year old Chrisdian Johnson of the murder of 16 year old Oluwaseyi Ogunyemi in South London.
No murder weapon was found at the scene. But, Dr Rob Ogden, using established human genetic profiling methods, was able to single out two dogs, an adult male pit bull-mastiff cross called Tyson, owned by Johnson, and an adult female pit bull-Staffordhsire cross called Mia, owned by a second man, who was later cleared of involvement.
The link to the attack was made after Johnson was arrested with his victim's blood on his hands and blood from Tyson on his body. Saliva from the second dog, Mia, was found on torn clothing in the park where the attack occurred in April 2009.
During the incident, both dogs also received several knife wounds.
At trial, the Old Bailey jury heard that the dogs were used as weapons to savage their victim first before he was stabbed to death.
After the verdict, Dr Ogden told reporters: "In the past we have been able to say we can identify something as coming from a dog and with profiles, if they don't match, we can definitely say they are not from the same individual."
But until now it was more difficult to prove a positive match, he added. The new technique "allows you to identify dogs to a fairly high level of certainty."
In a two-year study in collaboration with Edinburgh University, researchers analysed the DNA profiles of hundreds of dogs from around the country.
The statistical data they collected about the composition of each profile allowed them to work out the probability of the same profile occurring in more than one animal.
This information lets scientists say that the chances of a sample taken from a crime scene not being from a particular animal which has the same DNA profile is just one in a billion.
Dr Ogden said that the method is currently being used to investigate about half a dozen cases, including some involving dog abuse and neglect and two "pretty serious" dangerous dog allegations.
Detective Sergeant James Harper, one of the Police officers who worked on today's case, said: "We want to use this more often so if people are using status dogs or weapon dogs they are aware that we have got these processes and we can identify people from dog DNA."
ENDS