Lord Lucan could be living abroad after undergoing extensive plastic surgery, says the retired detective who spent five years on his trail.
Former Det Chief Supt Drummond Marvin – who is now 78 – has sensationally backed claims the killer aristocrat fled Britain for Africa.
And he fuelled increased speculation Lucan is currently living under a secret identity after his millionaire friends helped him escape.
He dismissed reports that the fugitive committed suicide after murdering his children’s nanny, insisting Lucan did not have the courage to kill himself.
His extraordinary claims come after Lucan’s brother Hugo exclusively told the Mirror he was “sure” he escaped to Africa after the brutal killing 38 years ago.
Speaking from his retirement home in Spain, Mr Marvin said: “I would say Lord Lucan probably was in Africa.
"it wouldn’t surprise me if he’s had plastic surgery and that’s been paid for by friends.
“If there was a vote among the police officers who were involved in the case, it would come out with a majority saying they thought he was still alive.”
Gambling addict Lucan was probably aided in his escape by wealthy pals with links to Africa, said Mr Marvin.
“He had friends with gold or diamond mines in South Africa and that would have been a good place for him to hide out, certainly before the end of apartheid,” the ex-detective went on.
“But I think he would have moved on from there at some point, to somewhere like Rio de Janeiro or, being a gambling man, to Macau in China or Hong Kong.
Flight: the aristocrat fled the scene after murdering the family’s nanny
The victim: Sandra Rivett, the nanny murdered by Lord Lucan
“However, if he has established an identity in, say, South Africa it would be difficult for him to up sticks and go somewhere else.
"That’s the thing that’s nagging me, that he is still in Africa.”
He dismissed the theory that Lucan – whose blood-soaked car was found in Newhaven, East Sussex – drowned himself in the English Channel.
“One thing I’m sure of is that he didn’t kill himself as has been suggested,” declared Mr Marvin. “We’d have found a body somewhere.
"it has been said that he’s lying at the bottom of the English Channel somewhere but I just don’t buy it. I don’t think he had the guts to kill himself, quite frankly.”
Lucan, who would now be 76, went on the run after nanny Sandra Rivett was battered to death and his wife Lady Lucan bludgeoned in her London home.
Detectives believe Lucan killed Sandra in the dark by mistake, believing she was his wife.
They say Lady Lucan then disturbed her husband, so he brutally attacked her too.
The crime, in November 1974, has become one of the most famous murder mysteries of all time.
Lucan’s younger brother Hugh Bingham told the Mirror last month in an exclusive interview he was certain the gambling addict had given police the slip and fled to Africa.
Lord Lucan has cosmetic surgery, Det Chief Supt Drummond Marvin believesPA
Speaking out: Son George talked to the Mirror yesterdayAP
The former secretary of the aristocrat’s close pal John Aspinall recently claimed that she had arranged for Lucan’s son George Bingham and one of his sisters to fly to Kenya and Gabon so their father could see them.
But earlier this week Lucan’s son George broke a 38-year silence to claim in an email: “I have not, to the best of my knowledge, seen my father since November 1974.”
Mr Marvin, who spent five years in charge of the case up to his retirement in 1988, claimed some of Lucan’s pals did not help the investigation.
“It was a cold case when I took it on but there was a sense of an orchestrated silence from his friends and the feeling he was being protected,” said Mr Marvin, who took over the investigation from Det Chief Supt Roy Ranson.
“I got the sense we hadn’t been helped as much as we should by people who should have known better.
“Friends are there to help but not when it comes to breaking the law. the files laid bare the ‘them and us’ attitude police were encountering at the time.
“Rather than people sympathising with the poor nanny who was murdered, you got people expressing sympathy with the lady who had to find another servant.
“I don’t think a great deal of pressure was placed on Lucan’s friends.
“Britain was more class-conscious than it is nowadays and they did have a pull.
"I wouldn’t say that hindered us a lot but I don’t think Roy Ranson got the assistance and honesty he should have got from witnesses.
“If the Lord Lucan case had happened today, I think he’d still have been helped, except that it would have been a little more difficult for his friends.”
Wedding belle: Lord Lucan marries Veronica DuncanDaily Mirror
Intended victim: Lady Lucan was brutally attacked but survivedDaily Mirror
The father-of-one, a Metropolitan Police officer for 28 years, said he thinks the case may benefit from a review by a Cracker-style psychologist.
Mr Marvin, who now writes crime fiction for a hobby, said: “It is frustrating that we haven’t been able to track down Lord Lucan.
"You’re paid as a police officer to prevent crime and if a crime happens you’re paid to solve it.
“We failed miserably in respect of Lord Lucan and that’s very frustrating.
£I think it would be a good idea to consult a psychologist or psychiatrist, give them the facts and see what they’d say. I don’t think it’s been done yet.
“The character of the man and his habits and traits would give a professional person a better idea of where he’s likely to go.
“We should ask them the question, ‘What would you do?’”
My dad Lord Lucan: Son breaks silence on mystery as police launch probe into new cluesI met Lord Lucan in Africa 30 years ago: former gangster's claimDetective who hunted Lord Lucan convinced the killer went to AfricaThe night of the killing: how Lord Lucan bludgeoned nanny to death and made his escape'My husband is dead': Lady Lucan dismisses claims he escaped to Africa"I haven't seen dad since 1974": Lord Lucan's son speaks out