A former care worker has been jailed for six years over a catalogue of rape and sexual abuse against vulnerable youngsters.

Gordon Collins groomed troubled children before molesting them at two children's units in Edinburgh over more than a decade from 1995.

Collins, 59, of Wolsey Avenue, Bonnyrigg, Midlothian, was convicted after a police cold case review sought out former residents in the homes.

Judge Lady Wise told him at the High Court in Edinburgh on Wednesday: "You have been convicted by the jury of an appalling course of criminal conduct consisting of predatory sexual abuse of four young girls in your care.

She said Collins had singled out victims for treats, outings or attention before exploiting them.

"All were extremely vulnerable and you were in a position of authority and trust to each of them," she said.

"You have shown no remorse for your actions and continue to deny responsibility for the offences while your victims continue to live with the consequences."

Lady Wise told Collins he would be on the sex offenders register indefinitely following his conviction.

Collins was earlier found guilty of indecency offences against four underage girls and the repeated rape of one of them.

The former assistant unit manager with Edinburgh City Council told his trial nothing had come of an inquiry into him instigated by social services in 1997, but he was later suspended after the diary of one of his victim's was found.

Collins first began his abuse in 1995, giving a 13-year-old girl cigarettes and sweets before kissing and touching her.

Another teenager was kissed, bitten on the neck and molested by him over a year during her time at a young person's unit.

A further underage girl was repeatedly raped by him over almost a year after he went into her bedroom at night in one of the units.

He cuddled, kissed and bit a 15-year-old on the neck in 2006 and told her he loved her while molesting her at a secure unit in Edinburgh.

Advocate depute Jane Farquharson told Collins' earlier trial: "Rather than care and protect, he has sought to exploit these children."

She said: "These are women who have absolutely nothing to gain by concocting lies against the accused."

The prosecutor said the abuse had occurred in the very places that should have been protecting the child victims who had "very troubled young lives".

One woman told the court how she had been abused by Collins and realised his behaviour was wrong at the time but did not tell anyone.

She said: "Who was going to believe me, the troubled kid, against him, a senior member of staff?"

During the trial, defence counsel Matt Jackson challenged the rape victim, now aged 26, that the indecent assaults on her between March 2004 and February the following year did not happen.

The woman, who cannot be named for legal reasons, replied: "It simply did happen and he knows that I know."

Collins was interviewed by police in 2006 after one of the victims had made a complaint to them but at the time it was considered there was insufficient evidence to bring charges.

Another woman contacted police in 2011 and gave an account of what had happened to her as a resident a young persons unit.

A cold case review was launched and police were given a list of all the female residents in the units at the time of the offences.

Officers went to detain Collins at his home early in the morning in November 2014 but found him walking at pace up a back lane.

Defence counsel Mr Jackson said Collins had been involved in charitable work throughout the adult part of his life and added: "He was in care as a young man."