In the early 1960s mums and dads were living in fear for the safety of their young sons.

Teenage boys were being abducted off the street into cars and taken to derelict premises – which had been specially rented – where they would be tied up, tortured and sexually abused.

Things got worse when it was discovered that one missing 15-year-old boy, Fred Dowden, had in fact been murdered.

Glasgow Times:

The whole country was horrified and there was pressure on the police to bring the fiend to justice.

They had quickly established that their suspect was using fake names such as Mr Green or Mr Blue to cloak his real identity. But police had no idea who he was or where he lived.

There was no CCTV in those days or forensic evidence like DNA which they could link to a suspect.

However, they did have an eyewitness.

A young apprentice aged only 14 walked into a Dumbarton police station and told the officers a terrifying tale.

He said he had been coaxed into a disused shop by a chubby man with a scar on his cheek who offered him ten shillings (50p) to help lift a fireplace grating.

Inside the dingy building the stranger produced a gun and tried to tie him to a chair and gagged him.

The youngster escaped and ran home to his dad who took him to the police.

Detectives were sceptical at first and wondered if the boy simply had a vivid imagination.

However, they changed their minds on discovering paint in the empty shop used to black out the windows, and a chair similar to what the victim had told them about.

The shop owner said the premises had been rented to a Mr Green whose description matched that given by the boy.

But despite extensive enquiries in July 1962 the trail to Mr Green went cold.

Then a few weeks later Fred Dowden vanished from his home in Dumbarton.

A massive police hunt assisted by members of the public and tracker dogs failed to find Fred.

It seemed hopeless until an eagle-eyed local PC John MacLeod noticed someone had used paint to black out the windows of a disused doctor’s surgery in the town’s West Bridgend area.

Remembering his boss’s orders to be on the lookout for anything like the earlier incident, the young police officer looked inside and saw a sight that made him sick to his stomach. Tied to a chair was the body of a teenage boy.

He had been suffocated, his face and mouth covered with tape.

Police were able to confirm his identity as missing Fred Dowden.

The surgery had been rented to a man with a scar calling himself Mr Black.

Horrified detectives then discovered a Mr Blue had rented another empty building in Govan in Glasgow a few weeks earlier.

Inside were rolls of sticky tape. The killer was obviously planning to snatch another victim. But who was the murderer? He had left fingerprints at the shop and surgery, but there were no matches in the police records.

The solitary clue police had was a possible sighting of Fred getting into a black Ford Anglia car on the day he disappeared.

Could that car be traced? It was a huge task requiring officers to find the owners of 9500 similar vehicles across the west of Scotland with no guarantee it was the motor the killer had used.

Hundreds of officers worked round the clock to trace the vehicles with one, PC Cameron Wiseman, making the breakthrough.

He had spotted a black Ford Anglia parked in a street in Parkhead in the East End of Glasgow.

Constable Wiseman found the owners and discovered they had been holidaying in Canada at the time Fred was abducted.

Glasgow Times:

But they had given permission for their mechanic Philip Givens to use the Anglia while they were away.

Could they describe him? They told him: “He’s chubby with a scar on his face.”

Givens, 35, was arrested at a property in nearby Dalmarnock that he shared with other family members.

His fingerprints matched those found in the Dumbarton shop and surgery; he was picked out at an identity parade and then positively identified by the owners of the premises as Mr Green and Mr Black.

At first Givens denied being responsible for the abductions including Fred’s murder but then broke down and admitted being the killer.

He told police that the devil had warped his mind when he murdered the teenager.

When Givens appeared at the High Court in Glasgow in March 1963, he pleaded guilty to abduction and murder and was sent to the State Hospital at Carstairs in Lanarkshire.

During the proceedings he showed little or no empathy for his victims.

It was also never explained why the Glasgow man had chosen Dumbarton for two of his victims including young Fred.

Psychiatrist Dr George Sweeney told the court the killer had a pathological sexual development adding: “Givens thinks of his abnormality in religious terms of the conflict between the devil and his good self.”

Before he was taken to Carstairs, Givens was overheard asking his sister: “How can I meet my maker? How can I face god after what I did for the devil?”

PC MacLeod, the man who found murdered Fred, went on to have a distinguished career in the police reaching the rank of Detective Chief Inspector. He retired in 1980 after 31 years’ service and died in 2013.

He was involved in 31 Scottish murder cases, all of which were solved bar one.

His one unsolved murder was the case of 63-year-old security guard Eddie Cotogno, who was found dead in his flat in Dumbarton in 1979, after it had been set on fire.

The prime suspect at the time was Angus Sinclair who was friends with the victim and had visited the flat in the past. But he had an alibi for the night of the murder.

MacLeod would not have realised that their suspect would prove to be more depraved than Givens – if that were at all possible – who he had helped put away as a rookie cop.

Sinclair was given a whole life term in 1982 for a series of rapes in Glasgow of young girls.

He was also later convicted of the murders of teenagers Mary Gallacher, Christine Scott and Helen Eadie.

Givens is understood to have spent most of his life in Carstairs and little is known about him following his incarceration. It is understood that experts took the view that he would pose a danger to children if ever released.

Givens also escaped the hangman’s noose. At the time capital punishment was still available to the courts.

In August that year factory worker Harry Burnett was hanged at Aberdeen Prison after he shot dead his lover’s husband.

Capital punishment was suspended in 1965 and banned in 1969.

However, the psychiatric evaluation presented to the court of Givens as criminally insane probably saved him from the gallows.

In other words, he was seen as mad rather than bad. Something that his victims and their families may not have agreed with.

At the time of his arrest, he had killed once and could easily have gone on to kill again. Certainly, he had at least one other abduction planned.

The police investigation had stalled at the time because he had no previous convictions and was not on the system.

They had been looking at men with a history of sexual offences against teenage boys.

But Givens at that time was simply not known to them. Also, they had never encountered a case like it.

At the end of the day, it was old fashioned police work that brought Givens to justice.

One detective said at the time: “We had nothing to compare it to.

“A man renting rooms using colour-coded names to abduct and torture teenage boys.

“Givens was highly organised and because he was not in our books it was almost as if we were looking for a ghost.”

Glasgow Times:

Crime writer David Leslie recalled the Givens case when he published a book about Carstairs’ infamous patients in 2015.

He said: “The search for Dumbarton teenager Fred had been a massive manhunt, only solved by an eagle-eyed PC who chanced upon his body in a disused shop.

“The solitary clue police had was a possible sighting of Fred getting into a black Ford Anglia car on the day he disappeared.

“After a trawl of 9500 vehicles in the city, they traced the car back to Givens.

“However, while in Barlinnie prison awaiting trial, his main concern was about who was looking after his beloved pet dog Bruce.”