Michael Ross did shoot dead a waiter as he served customers at an Indian restaurant, his own defence investigator has claimed, despite his lengthy campaign to clear his name.

Shamsuddin Mahmood, 26, was killed with a single shot to the head in June 1994 as he served customers at the Mumtaz restaurant in Kirkwall, Orkney.

Despite committing the crime in plain sight Ross, who was just 15 at the time of the execution which he committed from behind a mask, cheated justice for years.

The police officer’s son went on to join the Army, becoming a Black Watch sniper and rising to the rank of sergeant, but was finally jailed for the murder in 2008 and handed a life sentence.

Ross has always denied the murder but now even his own defence investigator, who worked to try and clear his client’s name, has said the courts found the right man.

George Thomson, whose role was to support the defence gather evidence in support of Ross’ case, told BBC documentary The Man in the Mask: An Orkney Murder he thought Ross killed Mr Mahmood.

Asked to explain why he thought this was the case, Mr Thomson told the BBC programme: ‘Information that we’ve got.

‘I went to England to trace a witness who had been there on the night, and we got a statement from that person.

‘And based on that statement. Yeah, I think he did. I can’t discuss, I can’t discuss them. That’s all I could say.’

On June 2, 1994, Mr Mahmood was at work when a man in a mask calmly walked in and shot him at point blank range in front of customers before running off.

It was the first murder on Orkney for a generation and took a remarkable turn when Ross, at that point a schoolboy, became the prime suspect.

At the time there was not enough evidence to charge him, but that changed 12 years later when a new witness came forward .

William Grant revealed in 2006 that he saw Ross with a gun and balaclava in public toilets near the restaurant where Mr Mahmood was shot, and police used that testimony to charge Ross for murder.

But during the trial at the High Court in Glasgow his credibility as a witness was repeatedly questioned.

He changed his story multiple times and was accused of having been given Ross’ name by a detective involved in the case whilst playing snooker with him in a masonic lodge.

Aamer Anwar, Ross’ defence solicitor, told the three-part series: ‘How did he even appear as a witness when he was so discredited? He was destroyed. Absolutely shredded in the courtroom.’

But, in response, Mr Grant said: ‘I was trying to do the right thing. I didn’t make it up. Something I’d never do.’

Ross, who is now 47 and was jailed for a minimum of 25 years, has made multiple escape attempts.

After Ross was found guilty he fled from the dock before being caught by a court official and police.

A hired car with a cache of guns and ammunition was later found in a nearby supermarket car park.

He also tried to escape while being taken to hospital in 2014 after he failed in a bid to have his murder conviction re-examined.

And in 2018 he tried to climb the fence at HMP Shotts, Lanarkshire, when prison guards intervened when he attempted to use a homemade ladder to scale the fence of a sports field while other prisoners were exercising.

The Man in the Mask: An Orkney Murder, 9.00 pm BBC Scotland, tonight, Tuesday, 25 November. All episodes available on iPlayer.