The Norfolk woman who helped catch Ian Huntley and the Suffolk Strangler
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She uncovered tiny grains of pollen which proved crucial in the capture of murderer Ian Huntley.
And her painstaking forensic work included investigating the 'Suffolk Strangler' - serial killer Steven Wright.
Leisa Nichols-Drew worked on forensics in major crime cases for the Home Office from 2000 after seeing an advert in the local newspaper.
From her home near King's Lynn she would travel to the Home Office lab in Huntingdon and sift through mountains of evidence in notorious cases, often under the gaze of international media.
In 2002 she was tasked to Soham after 10-year-old girls Holly Wells and Jessica Chapman had been murdered.
She was part of the "vehicle team" scouring Huntley's car for evidence.
"For such a massive investigation each aspect of the case was dealt with by a separate team so there was no chance of contamination," she said.
"We had groups of people looking at the school, the car and the house. The reason the vehicle was key in the investigation is it is a moveable item. You have got to look at the inside and outside for environmental connections that linked the car to where the girls were eventually found."
Pollen grains found beneath the wheel arch of the car linked it to the area where the girls' bodies had been found - near RAF Lakenheath.
"People can be very clever and attempt to remove evidence or clean up evidence," said Ms Nichols-Drew.
"You are dealing with microscopic pieces of evidence and it came down to pollen grains and soil samples.
"We took the car apart and looked for different pieces of evidence to see whether the girls had been in the car and where the car had been."
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The vehicle team worked scouring the car for several days in a secret location to preserve their work from the eyes of the media.
"You have only got one shot at it," said Ms Nichols-Drew. "When the car travelled from Soham it was covered in a tarpaulin but the media had a helicopter flying above it all the way to the lab.
"That could have compromised any court case so we had to conceal the lab so no one could get sight of what we were doing."
During her career Ms Nichols-Drew has worked on cold case reviews dating back more than six decades, and trained police officers and prosecutors in "forensic awareness".
"Evidence can be anywhere and in major crimes that can be crucial," said the 41-year-old. "Absolutely anything can be an evidential trace."
She added: "I worked on a stabbing case from the 1950s in which the knife had been tested so many times we had to take it apart and remove the handle to look for DNA evidence."
Ms Nichols-Drew also worked on the forensic investigation for the so-called 'Suffolk Strangler' case which helped catch serial killer Steven Wright, who killed five women in Ipswich in 2006.
"We were dealing with a very complex, challenging case because we had women who had gone missing quite close together and we were trying to look for any fibre traces or DNA traces to link those victims," she said.
But the secrecy of the work could be difficult, she said.
"You can't talk about it at home so you talk about it with your colleagues. We are only human and it can be hard when you can't find the evidence or you can't find who is responsible because they are not on the database."
Ms Nichols-Drew, now a lecturer in forensic science at De Montfort University, has just been awarded a National Teaching Fellowship.
"All of my lectures relate to genuine cases that I have worked on," she said. "I've even staged and created my own CCTV footage for students to analyse during a case briefing."
She replicates crime scenes and laboratory examinations that actually happened in the real world, to give undergraduates the experience of a fast-moving investigation.
This year, 54 people have been given National Teacher Fellowship status.