A SECOND high-profile murder case is being considered for retrial under Scotland's double jeopardy laws.

World's End killer Angus Sinclair was convicted of the rape and murder of teenagers Helen Scott and Christine Eadie on Friday, seven years after a court case collapsed against him.

The outcry over the collapse of his original case led to changes in the law to allow suspects to be tried again if "compelling new evidence" emerged. Sinclair, 69, who was jailed for 37 years for the murder of the teenagers in 1977, became the first to be prosecuted following the law change. He is believed to have killed at least 10 other people - making him modern Scotland's most prolific serial killer.

The details of the second case being considered under the double jeopardy legislation cannot be revealed for legal reasons.

Sinclair had already been convicted of two homicides, including the murder of his seven-year-old neighbour Catherine Reehill in 1961, when he was 16. He served just six years after pleading guilty to strangling the youngster. In 1982, he was given two life sentences after being convicted of three rapes and a series of sex attacks on young girls.

In 2001, following advances in DNA technology, he was convicted of the murder of 17-year-old Mary Gallacher from Glasgow in 1978.

But detectives believe he is the chief suspect in six unsolved killings in the 1970s - of five women and one man.

Forensic psychologist Dr Ian Stephen, the former director of psychology at Carstairs State Hospital who inspired the TV series Cracker, said it was likely Sinclair had killed many more.

He said: "It is one of those cases where he has got a behaviour or a type of killing which has been there since early youth and that is why people are saying there is probably a lot more than we know about.

"It is difficult to pick up as they [serial killers] are usually fairly isolated people. However, in this case, [Sinclair] was a fairly presentable guy when he was younger and had this ability to make an initial impact, which was the way he was able to attract people to him and make them feel safe.

"He used that as a technique for forming relationships - but also as a technique for getting hold of victims."

Stephen said Sinclair's personality was "very chilling" and he enjoyed the power of killing.

"He also loves the power of not saying anything to anybody," he said. "His interview with the police was classic - it's almost like a naughty child with the dumb insolence act."

Over the years, Sinclair's name has also been linked to the infamous Bible John killings. Between February 1968 and October 1969 three young women were found strangled, all of whom were thought to have met their killer at Glasgow's Barrowland ballroom.

Stephen said Sinclair would have been around at the time and there were similarities to the World's End case, as the victims had been out socialising.

He pointed out the police would have already investigated if there was any connection, but added: "It is never a possibility you can eliminate - as long as there is an unsolved crime."

Last night, a spokesman for the Crown Office said it would not be appropriate to comment or provide details on any other double jeopardy cases due to their status.