ESSENTIAL FORENSICS

Covert DNA use ‘vital for cold case success’

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Covert DNA use ‘vital for cold case success’

Use of evidence retrieval tactic proved vital for apprehending man responsible for historic sexual assault.

A ground breaking evidence retrieval technique to obtain covert DNA transformed the success of a serious cold case and is a “vital tool in the armoury of an investigator”, it has been suggested.

Chief Inspector Sean Memory, of Wiltshire Police, was one of the first to use the tactic in 2010 after it became enshrined in the 2008 Counter-Terror Bill, to pinpoint the offender of a sexual assault on two teenagers in 2001.

Keith Henderson (57), from Ribbleton, Preston, was jailed for 12-and-a-half years in July 2012 after being convicted the attack.

In an interview, Ch Insp Memory, who was also the Senior Investigating Officer (SIO) on the case, said that the technique is fraught with legal issues.

He added: “I made sure we went through all the legal arrangements and decisions to make sure we were watertight in our use.

“We also made sure we learnt lessons from where it went wrong. This was the first time we had used covert DNA retrieval in the force.

“It is a technique that is now at the forefront of our minds. It is a tool in the armoury of an investigator in a certain set of circumstances.”

A 16-year-old girl and her boyfriend, also 16, were attacked on Sailsbury’s Town Path by a man holding a gun. The boy was knocked unconscious and the girl was made to perform a sex act at gunpoint.

Initial investigations by officers and scenes of crime officers resulted in the retrieval of a DNA profile from a single sperm head. It is almost unheard of to have such a low level of sperm in such a case and therefore, great care was needed to preserve the exhibit and get as much information as possible.

More than 1,500 people were eliminated from enquiries. These were either people who were walking through the area around the time, who were nearby or were convicted of sexual assaults.

However, after 18 months officers had made no progress on the case and the trail went cold. Ch Insp Memory secured funding in 2007 to re-examine it and probed the familial links through the DNA profile. The case was featured on Crimewatch, which threw up 110 new lines of enquiry.

Officers established that the DNA profile was within the Henderson family through the male line. A database search linked the profile to one of Henderson’s sons, who had been convicted of a minor crime.

Armed with this information, Ch Insp Memory seized the opportunity to use covert DNA as part of a covert surveillance operation to catch Henderson.

After four days of surveillance, Henderson, unaware that the police were onto him, went to a coffee shop for a hot drink. Once he left the premises, officers worked quickly to retrieve the cup and obtain a full DNA profile from the lip of the cup.

Ch Insp Memory said: “Once we had that we knew it was definitely him and knew it was not some other relative. It left me reassured that we had the right person.

“We only use the covert DNA purely for intelligence. Once we had him we could obtain another DNA profile to use as evidence.

“He never knew we were on to him and had been walking around a free man for 10 years. When we caught him you could see the amazement that we had caught up with him.”

Henderson was found guilty of assault, possession of an imitation firearm, two counts of unlawful imprisonment and indecent assault.

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