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He's the famed ex-detective who caught Milly Dowler's murderer and the Night Stalker rapist, one of Britain's most depraved sex attackers.
Now Colin Sutton has turned his attention to a controversial murder case that led to two secret trials and claims of a miscarriage of justice.
The former senior Met Police officer was involved in the early stages of the investigation into the killing of reclusive millionaire author Allan Chappelow in 2006.
Chinese dissident Wang Yam was convicted of the murder in 2009 despite evidence against him being, in the words of the court, "entirely circumstantial".
Yam, who was widely reported to be an MI6 informant, continues to protest his innocence from behind bars - and questions have been raised about his conviction since his trial.
Mr Sutton has now re-examined the case in his Sky Crime series The Real Manhunter - one of 10 investigations he retraces as the programme returns for a second season.
The former detective chief inspector tells Sky News that reviewing the Chappelow murder case has given him "the opportunity to look at aspects of the evidence and the investigation, of which I was previously unaware".
'A really evil, calculated killer'
Having re-examined the case, Mr Sutton says he has "no doubts" about the identity of Mr Chappelow's murderer.
"I think it was a sound and solid conviction for a really evil, calculated killer who was out to make money and solve his debt problems," he says.
"I think the evidence that Wang got and used (Mr Chappelow's) cards and effectively stole his money was pretty overwhelming.
"The degree of planning, and the method and process by which the crime was accomplished, leaves me with very little doubt at all."
Asked whether the secret element of the trial may have fuelled beliefs that there had been a miscarriage of justice, Mr Sutton replied: "Quite possibly so.
"It was a remarkable thing from a legal history point of view to have a murder trial conducted in secret.
"That was because of the nature of his defence and the fears that it would be detrimental to national security if it was held in public.
"It's another layer of intrigue to what is, in any case, a very interesting investigation."
It was reported earlier this year that Yam had given information about telecoms giant Huawei to a parliamentary committee while serving his prison sentence for murder.
Mr Sutton says: "It shows the kind of circles in which he mixed and it shows there was certainly something to his knowledge.
"There's no doubt he was well-connected through his family to the Chinese Communist Party and had some knowledge of affairs over there - it doesn't mean to say he didn't commit the murder."
'Levi Bellfield - never believe a word the man says'
Mr Sutton's work to catch serial killer Levi Bellfield - who murdered schoolgirl Milly Dowler - and the Night Stalker rapist Delroy Grant was portrayed in the ITV drama series Manhunt, starring Martin Clunes as the detective chief inspector.
In recent months, Bellfield has purportedly confessed to the notorious hammer murders of mother and daughter Lin and Megan Russell 26 years ago, and requested a prison wedding.
Mr Sutton - who came face-to-face with the killer after his arrest - says Bellfield is "unfortunately quite keen at getting himself into the headlines".
"Every time he does I have to switch my phone to silent because the world and his wife are trying to call me to talk about it," he adds.
"In some ways I kind of take a step back from it.
"The best rule of thumb when dealing with Levi Bellfield is never to believe a word the man says."
Mr Sutton says Bellfield's request for a prison wedding "seems bizarre" for "somebody who was so violent towards women, has killed women, (and) was entirely misogynistic for his entire life".
"I think he likes to keep himself relevant," he adds.
"I'm not sure it will pan out in the way we might think it might."
'Heartily sick' of partygate
Mr Sutton says a third series of The Real Manhunter could move away from murder cases but there is one investigation he won't be re-examining - the Met's partygate probe.
"I'd want to keep as far away from partygate as I possibly could," he says.
"I think like many people, I'm heartily sick of it all."
Mr Sutton adds: "I take a great interest in serious crime and how it's investigated. I've got friends and indeed family still within the police and I keep in touch with what goes on in that way.
"I've got the upmost respect - the job is more difficult these days than it ever was.
"Those who carry on doing it just have my admiration and respect."
Met Police controversies
The Metropolitan Police has faced a series of recent scandals including the conviction of officer Wayne Couzens for the murder of Sarah Everard and evidence of misogyny and discrimination within its ranks.
But Mr Sutton, who retired from the Met Police in 2011, believes cultural problems within the force had improved over his 30-year career.
"The Met that I left in 2011 was nothing like the Met I joined in 1981," he says.
"There's always room for improvement. Police officers are taken from society and society has these elements of sexism, homophobia and racism sadly within it.
"I think the answer to it is not for people to send emails from on high.
"The actual answer is at the working level with the first and second line supervisors - the sergeants and the inspectors - there needs to be leadership there.
"You can't show leadership sitting behind a desk on a computer. You have to be there with the people to do it.
"I think that's the shift in managerial culture that will be needed to promote the change in actual culture."
Mr Sutton says he hopes the new series of The Real Manhunter - which features the first murder case he worked on as a detective inspector in 1992 - showcases "just how good police can be in serious crime".
He adds: "There are lots of reasons for that - reassuring people and, I suppose, waving the flag slightly in what are difficult times for the police."
The Real Manhunter series 2 launches on Sky Crime and streaming service NOW on 13 June.