Hertfordshire has seen many a gruesome and grizzly crime, but not all of them have been solved.

We previously covered 5 mysterious unsolved murders that shocked the county, and here are five more that remain without answers to this day.

1. Mustafa Zarif

Mustafa Zarif was found by a dog walker, buried in a shallow grave in Nine Acre Wood near Essendon in April 1996, although it is believed that he was killed four months prior whilst being driven to a dinner appointment in late 1995.

Two Turkish men were tried twice for the murder of the 32-year-old but found not guilty on both occasions. The court heard that there had also been a third man involved who had fled to Cyprus.

At the trial, evidence was heard from a convicted heroin dealer, who claimed the trio, who were described as a "murder squad", lured Mustafa Zarif to his death and strangled him, before dumping his body off Cucumber Lane.

The two men tried for his murder were later part of a quartet jailed for a total of 87 years for drug smuggling, which was said to have been connected with Zarif's murder. One of the men, described as the 'Mr Big' was sentenced to 26 years.

During the trial, Woolwich Crown Court heard that their drug network stretched from London to Scotland, and had involved the supply of 400kg of heroin, worth more than £64m.

A prosecution witness who claimed he was present when Zarif was murdered was later jailed for 15 years in October 1996 after being found with 40kg of heroin, but had his sentence reduced to eight years on May 1997.

2. Joan Macan

Joan Macan was a renowned dog breeder and a Second World War heroine, who helped more than 80 Allied airmen to escape across enemy lines while living in France under a fake name.

But, on Friday, May 6, 1988 - the day of her 81st birthday - she was murdered outside her own home on the Ashridge Estate.

The Comet: Joan Macan.Joan Macan. (Image: Newsquest)

Having spent the night at a meeting of the Kent, Sussex and Surrey Labrador Association 60 miles away, she left around 11pm for the long drive home.

Back at her home, the housekeeper had locked up and left the lights on at around 9.40pm, but it was at around midnight that strange activity was noticed by witnesses.

A couple courting in a car park on the Ashridge Estate lane that led to Joan's house spotted a dark four-door saloon car travel up and down the road around six times, but they were unable to identify the make or model.

Then, at 1am, they saw an estate car, which they believed to be Joan, head down the track to the property. It is believed that Joan was murdered as she walked from the vehicle to her front door.

The couple then saw an estate car drive back up the track at around 1.30am, which they believed was being used by the killer or killers.

A number of distinctive items were stolen from the home either before or after the murder, which officers believed would be key to solving the crime, but Joan's killer has never been identified.

3. Wayne Trotter

Wayne Trotter was working home from work just after midnight on December 5, 2002, when he met a horrific end.

The 30-year-old had travelled from Cricklewood to Borehamwood on the bus, and was just yards from his house in Farriers Way estate when he was set on fire by his killer.

The Comet: Wayne TrotterWayne Trotter (Image: Herts police)

After being set on fire, Wayne somehow managed to knock on the doors of five houses, with neighbours throwing water and blankets over him. Despite their best efforts, he had suffered serious burns to 90 per cent of his body and his life could not be saved.

There did appear to be witnesses in the case, with a woman heard screaming just before he was discovered on fire. Police appealed for the woman to come forward, but she never did.

Two teenage boys were arrested shortly after his murder on December 18, 2002, but no charges were brought against them.

Officers took 750 statements, made 1,600 house visits and followed more than 2,500 leads during the investigation, named Operation Refit, but Wayne's murder has never been solved.

Renowned detective Peter Bleksley featured the case in his debut book, and appealed for more information on the 20th anniversary of the case.

Speaking to the Borehamwood and Elstree Times in 2005, he believed Wayne's killers had "no intention of murdering anyone" that night, and were instead trying to commit arson on a community centre.

"As Wayne walked home, I believe they saw him and panicked," he said.

"They thought he might be able to identify them to the police and in an effort to evade capture, they used the element of surprise to jump him.

"A criminal enterprise such as this leads to an inevitable adrenalin rush, and, as a result, things got fatally out of hand. In a few moments of unplanned madness, they managed to ensure they would be wanted by police for the rest of their lives."

4. Diana Suttey

On September 7, 1956, at around 3.15pm, three boys made a shocking discovery in the bushes on Green Lane in Leverstock Green. It was a body.

It was that of 36-year-old Diana Suttey, who had been strangled with a pink and white scarf and then dumped.

Police believe she had been murdered by a man that she had met secretly on a number of occasions in Hemel Hempstead, but a key piece of evidence came in the form of witnesses.

A blue saloon car with the registration number SUU 138 had been seen Green Lane at about 3pm on the day Diana's body was found.

Despite searching 30,000 cars, 150,000 vehicle owners being interviewed, and the case being the first of its kind where the police had used teeth marks to try to identify a murderer, no suspect was ever found.

It is believe she struggled with her attacker in the rear of the car, somewhere along the three-mile stretch of road before being killed. There were just 15 minutes between the car being seen and her body being found.

An inquest into her death concluded on February 12, 1957, with a verdict of murder by a person or persons unknown returned, and the case remains unsolved today.

Diana's case bore striking similarities to the murder of four other women, Jean Townsend - who was dumped not far from where Diana was found - Hellen Carline in September 1954, Muriel Maitland in 1957, and Gloria Booth in 1971.

5. Stephen Varley

On Saturday, December 18, 1948, Stephen Varley took his 10-year-old daughter to a children's party at the de Havilland aircraft factory in Hatfield, which is also where he worked as a shop steward.

He was seen exiting the party at de Havilland around 7pm that evening, leaving his daughter with a friend. At around 9pm, he was seen again, this time catching a bus to nearby St Albans, arriving at 10.30pm.

The Comet: Stephen Varley.Stephen Varley. (Image: Herts Ad)

Stephen was then spotted by witnesses walking with two men along Cotton Mill Lane between 10.30pm and 11.10pm, near to the Sopwell Ruins and allotments, with some reporting him to be drunk.

At around 11.15pm, he was seen struggling with the two men on a footpath next to the allotments, and this was the last sighting of the 52-year-old.

At around 8am on Sunday, December 19, his body was found lying amongst the vegetables. He had been beaten, strangled and left with his head and face badly battered.

The mysterious murder drew the attention of chief detective inspector Robert Fabian of Scotland Yard, and Dr Keith Simpson, an eminent forensic pathologist, but they had little to go off.

His injuries were consistent with being attacked by more than one person, and while his work with the trade unions could have made him a target, it seemed as if his murder was unprovoked and not premeditated.

True crime fanatics speculate Stephen was just in the wrong place at the wrong time, and that he was the victim of an attempted robbery gone horribly wrong.

With his murder still unsolved almost 75 years on, we may never know who killed Stephen Varley.