A TELEVISION show which is being broadcast this evening will examine the horrifying murder of a Colchester schoolgirl who was killed in front her son.

Cold Case Forensics, a new three-part crime documentary, will air its first episode on ITV tonight focussing on the death of Rachel Nickell.

Rachel, a former Colchester County High School for Girls student, was stabbed 49 times and sexually assaulted when she was just 23-years-old.

The attack took place while she was walking her dog on Wimbledon Common and unfolded in front of her two-year-old son Alex Hanscombe.

For years Rachel’s murder had been one of the UK’s most high-profile cold cases until paranoid schizophrenic Robert Napper, 42, eventually admitted manslaughter on grounds of diminished responsibility.

Gazette:

During the opening episode of Cold Case Forensics, Dr Angela Gallop will explore how DNA evidence produced a vital breakthrough.

She will also delve into exactly how her team helped solve the 1992 murder, for which a man named Colin Stagg was initially the main suspect.

Dr Gallop and colleagues were parachuted in to re-examine the evidence gathered for the case after Stagg’s trial collapsed, with the judge criticising the police's tactics.

It soon transpired that minimal DNA evidence had been recovered from swabs and tapings taken from Rachel’s body.

Dr Gallop said: "When we were faced with a sample that hadn't given any DNA results at all we knew that something was very wrong.

“You can't have that sort of finding without finding a proper explanation for it. You can't have a loose end like that. Forensic scientists don't like loose ends."

Gazette:

Over the next two years Dr Gallop's forensic profiler Andy McDonald and his team worked to develop a new process which would allow the search for DNA to continue.

The result - known as DNA enhancement - revealed a match to DNA found on Rachel's jeans, which proved a huge step forward in the case. 

At the time of the discovery Napper was already locked up in Broadmoor Psychiatric Hospital for a vicious double murder of a mother and daughter.

He had also previously admitted his part in a string of rapes and attempted rapes which had striking similarities to Rachel’s killing.

Dr Gallop added: “There was satisfaction in knowing someone who committed this absolutely horrendous crime had been identified and justice had been done insofar as it ever could be for Rachel and her family.”