Retired detective Dave investigated and solved some of Britain’s most sickening murderers. Today he recalls the cases that still haunt him – and the two killings he is still furious he could not break.

Dave had accepted demotion to join the Cheshire police force in 1986 after he left the RUC.

But he quickly moved up the ranks, becoming a detective inspector for the second time in his career.

As a result, Dave found himself at the heart of these high-profile investigations.

Dave’s team were stumped until they identified killer Stephen Mottram through the use of controversial Low Copy Number DNA profiling to analyse single cells left at the scene.

Mottram, 40, from Cheshire, was convicted in 2007 and will serve 16 years.

Dave said: “It was a difficult and long case, and thank God we were able to use the DNA tests.”

This have-a-go hero dad, 47, was kicked to death by a group of feral youths outside his Cheshire home.

Dave Edgar’s work on the case, the same month Stephen Mottram was convicted, led to his three teen killers being sentenced to life.

Dave was also awarded a judge’s commendation for his work on the case.

“It’s not the award that made the case rewarding,” he said. “It was seeing the perpetrators brought to justice.”

This mum-of-two was doused with petrol and set alight just before Christmas in 1994.

The killers dumped 31-year-old Tracey’s horrifically burnt body on the steps of a church in Cheshire and she died a day later.

Despite interviewing 2,000 people, Cheshire cops have never been able to trace the kidnappers.

“It’s just one we couldn’t get,” Dave said. “A horrific case.”

Unemployed Craig Smith abducted this 13-year-old in 1999 as she walked home from school in Cheshire.

He shot her with an air rifle, strangled her and her body was found five days later in the fast-flowing River Dane.

Dave said: “I was one of the first on the scene and found her body covered in horrific injuries. But it’s just something you’ve got to deal with.”

Dave admits he is still fuming he could not snare this Asian girl’s killers.

Her body was found badly decomposed on a river bank in Cumbria five months after she vanished on her way home from work in September 2003.

Dave suspected an “honour killing” but the killer or killers were never brought to justice.

A coroner ruled last year that Shafilea was murdered after rejecting an arranged marriage.

Before her death, Shafilea drank bleach in an act of self-harm.

Dave said: “It’s the one that got away for me, and the one I’ll always be bitter about.

“It was horrific to find her body so badly decomposed in that river. Honour killings these days are getting out of control.”