A MURDER trial witness whose evidence helped snare three killers is behind bars after raping two women.

Shaun Sinclair, from Saltcoats, was today locked up for eight years for the terrifying sex attacks.

Sinclair raped one after lining up knives on a table and asking the woman what one she “wanted to die with”.

The 23 year-old returned to the High Court in Glasgow after being convicted last month.

A judge told him he was guilty of “truly despicable behaviour”. Sinclair will also be monitored for four years after his release.

Just two years ago, his testimony led to three people being jailed for the torture and killing of a vulnerable man in Saltcoats.

Sinclair was a vital prosecution witness in describing how Scott Blackwood was brutally attacked before attempts were made to set him on fire.

Allan Nicol, 36 and Thomas Moore, 26 were locked up for murder while Georgina Smith, 22 was jailed for culpable homicide.

But, Sinclair ended up in the dock himself after women revealed how they suffered at his hands.

He raped a former partner in April 2014 having earlier had sex with her when she was only 15.

Sinclair regularly cheated with other women – but the victim admitted she would “jump off a bridge” for him.

He struck after initially ordering her out a flat in Glasgow's southside before demanding she return.

When he met her, Sinclair chillingly told her: “You're going to get a shock when you go in.”

The victim said she knew “something bad was going to happen”.

As she entered, kitchen knives were spread on the table – and Sinclair told her to pick the one she wanted to die with.

In his speech to the jury, prosecutor Bruce Erroch said: “What calculating behaviour...I say it borders on sadism.”

Sinclair punched and tried to choke her. Struggling for breath, Sinclair went on to rape the woman.

The court heard Sinclair had “battered her black and blue to overcome her will”.

Sinclair then carried out a separate sex attack that day leaving her in tears.

The woman did go to the police – but controlling Sinclair made her withdraw the allegation.

It was put by Sinclair's lawyer the sexual violence did not happen – but the distressed victim replied: “So, I gave myself two black eyes?”

He raped her again on Christmas Eve 2014 – after leaving her to go and have sex with a neighbour.

She recalled him coming into their Ayrshire flat looking “dead vicious... making gestures as though he was going to kill me”.

He trashed the flat before dragging her by the hair yelling: “You are making me do this”.

The woman said Sinclair spoke about “finishing her” as he whipped out a blade.

The court was told he initially put the knife to her throat before “sawing” at her hand.

She said Sinclair stood over her “like a sacrifice” as she feared he was going to plunge the blade into her.

The woman dodged the weapon, but Sinclair still managed to stamp on her face and body.

Not satisfied at leaving the woman battered, a raging Sinclair went on to rape her.

Sinclair also raped another woman at a house in Girvan, South Ayrshire in January 2013.

He attacked her after smashing up the property. The woman had tried to calm him down, but, instead, Sinclair grabbed her wrists and forced himself on her.

Sinclair was convicted of having unlawful sex, assault and rape against the first woman.

He was found guilty of raping the second woman as well as physically assaulting a third female at a flat in Largs, in April 2012.

Sinclair was further found guilty of having sex with another 15 year-old girl in 2013.

Judge Norman Ritchie QC told him: “Your behaviour was truly despicable.

“Violent offences, vicious assaults...a clear course of conduct against young women who had the misfortune to know you in life.”