A RETIRED detective who helped to bring Elaine Doyle's killer to justice after 28 years says it was an honour to get justice for her family.

Former Detective Sergeant Mairi Milne features in a new TV documentary being broadcast this month about the Greenock murder investigation, which finally ended in 2014 when killer John Docherty was sentenced to life behind bars.

Mairi says the end result meant it was 'the most satisfying inquiry I have ever worked on in my 30 years in the police force'.

She said: "From the day I started as a police officer in Greenock in 1988, everyone knew about the inquiry.

"It was a great honour to see it through and come to a satisfactory conclusion for the Doyle family."

Mairi had been working on the 1986 murder since 2008 and every so often, technology and forensic opportunities would help police bring the police a step closer to a result.

In 2012, officers got the crucial breakthrough they had been waiting for.

Mairi said: "I received an email saying we had a DNA match to John Docherty.

"I don't think I've got words to describe how I felt.

"We had always spoken about ,'who will it be?' and if we would eventually get a result.

"I was stunned, I read the email and it said we had a one-in-a-billion hit."

Docherty has always protested his innocence but he failed in his appeal and Mairi says the guilty man was caught, prosecuted and locked up.

Mairi said: "The person who murdered Elaine has been found guilty and convicted for it."

The case was one of Scotland's most high profile murders and left a lasting impact on the minds of local people.

Mairi said: "Murders in 1986 were few and far between, especially of a child.

"Elaine was only 16 and that hit home.

"She was just a young girl with her whole life in front of her.

"It was a small close-knit community and a lot of people knew Elaine, her brother and her mum and dad.

"They wanted to get answers as well.

The retired officer says the TV programme about the case is important as it will allow remaining family and friends and the local community to once again remember Elaine.

Mairi said: "The inquiry has been in the memory of the people in Inverclyde for such a long time and people still feel it is very personal to them.

"Everyone knew about Elaine Doyle.

"People remembered where they were and what they were doing when Elaine died.

"I think friends of Elaine will find it comforting to be reminded that the killer was eventually caught, convicted and sentenced."

Mairi built up a close relationship with Elaine's family over the years, especially with her late parents Jack and Maureen.

She said: "I started in 1988 and was only eleven days younger than Elaine.

"I had a very good relationship with Maureen.

"Sometimes she would think about what Elaine would have done, if she'd got married and had children, how her life would have been different."

Sadly Elaine's parents Jack and Maureen and her brother John have all now passed away but her mum and brother were still here to see justice being done.

Mairi said: "I remember speaking to Maureen that morning we had caught Elaine's killer.

"She was hugely emotional.

"She'd prayed for that day for so long.

"I was only disappointed that her dad Jack passed away without knowing.

"He was in the town centre every day and would wonder if the person had walked past him, or if he had spoken to them."

Jack bravely took part in a public appeal held on the 25th anniversary of his daughter's death.

Mairi said: "He was hugely supportive of the police.

"My only regret is Jack died without knowing."

During the trial much was said about the police investigation at that time, including the mistakes that had been made.

But Mairi said the officers at that time did what they could with the limited resources they had.

And while forensic science played a pivotal part in snaring Docherty, old-fashioned policing and public co-operation had a crucial role too.

Mairi said: "A witness who saw John Docherty at the scene that night could still identify the person 26 years later.

"There is still the element of human common decency."

Mairi says Docherty's profile is unusual because as far as police know, he never committed a crime before or after the murder.

She said: "Murder is at the top of the scale and not to have committed or been caught for a crime again for all those years is highly unusual.

"He also worked locally and stayed locally.

"I don't know what he thought when he saw the appeals in the Telegraph.

"He lived the life of a father and partner and slipped under the radar."

* Murdertown - Episode 7, Greenock is being screened on Monday October 28 at 9pm on the Crime and Investigation channel.