KATHMANDU (AFP) -- A Nepalese policemen, who refuses to forget a childhood memory of the half-burned body of a slain American woman, is now investigating detained serial killer Charles Sobhraj over the murder which took place 28 years ago.

Deputy police superintendent Ganesh K.C., now 40, said the law must take its course and determine whether the infamous killer had anything to do with the 1975 murder of the young American and that of a Canadian man in the Nepalese capital.

Sobhraj, 59, who spent 21 years in Indian prisons for murder, has denied involvement in the Kathmandu murders. He has also denied that he has ever visited Nepal before. Sobhraj has not yet been formally charged with the murders.

Ganesh has been investigating Sobhraj, who has been accused of leaving a trail of 20 bodies of young Westerners across Asia during the 70s and 80s, since he was arrested in Kathmandu last month.

"When he visited Nepal for the first time in 1975, Sobhraj came with a fake Dutch passport issued in the name of Bentinja Henricus," Ganesh alleged in an interview with AFP.

"And this time he entered Nepal on September 1 with a French passport," he said of Sobhraj, whose Vietnamese mother remarried a French soldier giving the serial killer his present nationality.

Ganesh, a hardened detective, said ever since he was a child he had wanted the killer of American tourist Connie Bronizch to get the maximum sentence.

Bronizch and young Canadian hiker Laurent Armand Carriere were killed in Kathmandu with their bodies partly burned in 1975.

Nepal charged Sobhraj with the double murder in 1976 but by then he had fled, allegedly using Carriere's passport. If convicted of murder, he could face life in prison. Nepal does not have the death penalty.

Legal experts, however, say prosecuting Sobhraj would be a Herculean task for Nepal's tiny judiciary. He has been represented in the past by top French lawyers and has allegedly stolen the passports of his victims to travel across countries unhindered.

Sobhraj claims he came to Nepal to research a documentary film on handicrafts.

Ganesh said he is unable to wipe away the memories of the body he saw when he was 12 years of age.

"When I saw the body of the naked woman I was shocked and had since then wished that the criminal who did this should be severely punished," Ganesh said. He said it was "sheer luck that I got the chance to investigate the same case."

Sobhraj was released from prison in India in 1997 after serving 21 years for poisoning to death a French tourist and murdering an Israeli man. He briefly escaped from there as well by serving his guards sweets and grapes laced with sedatives.

Sobhraj was born in Saigon, now Ho Chi Minh City, the son of an Indian businessman and a Vietnamese woman.

Young Sobhraj began a criminal life after his French father took the family to Marseille. Soon the criminal graduated from petty crimes to murder and jewelry heists.

Sobhraj would later call his life a protest against the French legal system and a show of his love for Asia.