CALLS have been made for a review of the police's dealings with murdered businesswoman Lynda Spence after it emerged she had been recruited as a gangland informant before she disappeared.

Senior officers have been urged to fully examine its work with the 27-year-old as two men, Colin Coats and Philip Wade, were convicted at the High Court in Glasgow of her kidnap, torture and murder.

Coats was sentenced to 33 years in prison – one of the longest jail terms ever handed down by a Scottish court – and Wade imprisoned for 30 years in a crime noted by Solicitor General Lesley Thomson for its "extraordinary brutality".

Ms Spence's body has never been found, and officers last night urged her killers to show "common decency" and divulge where they disposed of her remains.

She had been held at a flat in West Kilbride, North Ayrshire , as Coats, assisted by Wade, tried to force her to reveal the whereabouts of at least £85,000 he had given her as the pair's financial deals started to unravel.

Her thumb and fingertip were chopped off with garden loppers and her legs smashed with a golf club as the torture intensified on Ms Spence, who had a professional front as a financial adviser but was involved in her own string of fraudulent deals and owed tens of thousands of pounds to her associates.

The spotlight is now on her relationship with police after it emerged she was approached by two officers of the then Scottish Crime and Drug Enforcement Agency (SCDEA) at Glasgow Airport on March 11, 2011, and asked to inform on a suspected Albanian drug dealer, Sokol Zefaj – who Ms Spence claimed she had been married to – and three other men.

A deal to secure her as an informant was made on April 14, the day she was abducted from Broomhill in Glasgow.

Ms Spence's handler at the SCDEA was told of her disappearance within 48 hours, the court heard, but investigating officers from Strathclyde Police were left unaware of her link with the elite unit.

If working as an authorised Covert Human Intelligence Source (CHIS), her safety and welfare would have been protected under law. However, it is unclear at this stage how much the territory in which she worked for the SCDEA overlapped with that inhabited by Coats and Wade.

Lewis Macdonald MSP, Labour justice spokesman, said the relationship between police and Ms Spence should now be reviewed following the conclusion of the high-profile 10-week trial. He said: "The relationship between the police and informants can be difficult, complex and needs very clear guidelines.

"I hope that, given the prominence of this trial, Police Scotland considers a review into how Lynda Spence was dealt with. Police often deal with people living chaotic lives and, where someone who is being paid as a police informant is killed or prosecuted for criminal acts, then it is only right that how that informant was managed by the police is reviewed."

A spokeswoman for Police Scotland said: "The inquiry established no evidence to suggest that Lynda being a CHIS was a motive for her murder."

The jury of six men and seven women yesterday found Coats unanimously guilty of the murder and subsequent clean-up of evidence.

Wade was found guilty of the murder by majority verdict and unanimously guilty of the clean- up, with the jury clearing him of chopping off Ms Spence's head.

Just a single spot of Ms Spence's blood had been found in the house but a vast, circumstantial case was built up against her two killers.

Coats, a former IT specialist who has a conviction for air rage, and Wade, a self-confessed drug dealer and enforcer of drug debts, shook their heads in the dock as the verdicts were returned. Minutes later Coats was served with an order under the Proceeds of Crime Act and said: "Oh, thanks very much."

David Parker and Paul Smith, who "babysat" Ms Spence during her captivity, had originally been charged with murder but admitted a lesser charge following a deal with the Crown that led them to turn on Coats and Wade and give evidence against them. They were both sentenced to 11 years yesterday.

Ms Spence's parents, Patricia and Jim Spence, said: "There is no verdict that will bring our daughter Lynda back or spare her the terrible ordeal that took her life. We will never begin to imagine her suffering or comprehend the cruelty of any person who would do that to another human being.

"We cannot begin to understand or forgive what they did to our daughter, Lynda. No words can begin to describe the heartache and pain we are suffering."

Detective Superintendent Alan Buchanan, officer in charge of the murder investigation, said he hoped her parents could now rebuild their lives.

But he said: "The pain for the Spence family continues. I would appeal for those convicted to show some common decency and tell us where Lynda is in order we can get her back to her parents and allow them to grieve properly."