|Sean Flynn with his famous actor father Errol|
The expedition team had scoured the dense jungle in the remote north-east of Cambodia for months before unearthing bones and teeth.
Photojournalist Sean Flynn was just 28 when he disappeared in 1970 during a Time magazine assignment as the war spilled into Cambodia. It became one of the conflict's most celebrated mysteries, but it now seems clear that he was seized and executed by brutal rebel soldiers belonging to Cambodia's Khmer Rouge.
His grieving mother Lili Damita, Errol Flynn's first wife, spent huge sums on failed expeditions to find Sean's body before she died in 1994.
Now, in a search part-funded by Sean's half-sister Rory, adventurers David MacMillan, a Scottish-born Australian, and Briton Keith Rotheram have unearthed the remains of an executed Westerner who they believe is Sean.
He was the image of his movie idol father, the star of films such as The Adventures Of Robin Hood. The remains include four well-preserved teeth, two of them still bright white.
They were handed over to US Embassy officials in Phnom Penh on Friday and are being flown to America for DNA tests and to be checked against Sean's dental records.
MacMillan, 29, and Rotheram, 60, hired bomb clearance experts, a bulldozer and teams of local workers to dig at a site where a witness described a tall, blond Westerner matching Sean's description being executed in 1971.
The witness said the man was forced to dig his own grave and then battered to death with a rock after his executioner's gun jammed as he tried to shoot his victim in the back of the head.
The finds at the site include prisoner's clothes, jungle vines used to tie up a prisoner, bone fragments and the teeth.
|Sean, a war photographer, went missing during the Vietnam war in 1971|
Previous theories about his disappearance – immortalised in the song Sean Flynn on The Clash's classic Combat Rock album – include execution by lethal injection in 1970.
But witnesses in the village of Phka Dong in Kampong Cham province, where the remains were found, said a man matching Sean's description was one of five foreigners held prisoner there by the Khmer Rouge until 1971.
According to the witness of the execution, who was a buffalo boy at the time and used to take baguettes and cigarettes to the prisoners, they were kept bound and chained and taken one at a time to execution sites near the village.
MacMillan, who lives in Vietnam, and Rotheram, who runs a bar in Sihanoukville in Cambodia, say that they have spent about £7,000 on their expedition.
In an email from the US, Sean's 53-year-old sister Rory, Errol Flynn's daughter from his second marriage to Nora Eddington, said: 'I grew up with Sean and also named my son after him, so we have hoped and prayed that his remains would be found.
Information came to me in the past year that motivated this private search and we hope that the person found is my brother so that he can finally come home.'