When the doorbell rang at Cock Cottage on the evening of 7 January, retired lieutenant-colonel Robert Riley Workman paused from preparing supper and slowly made his way to the front door at a pace dictated by his arthritis.
The events that followed left the 83-year-old lying in a pool of blood with a fatal shotgun blast to the chest and marked the start of a murder inquiry that bore more resemblance to a classic Miss Marple case than a 21st-century homicide.
The reclusive colonel had left a large amount of money in his will; the murder weapon was an unusual firearm designed to kill large animals; and an anonymous 999 call was made by the suspected killer.
But despite a number of clues at the start of the investigation, police have admitted that the motives for the killing remain unknown - and residents of the picturesque Hertfordshire village of Furneux Pelham continue to live in fear that the killer is among them.
Yesterday, 51 days after the murder, the victim's family made an emotional plea for information. Kenneth Workman, the colonel's nephew who travelled to Hertfordshire from his home in Australia, tried to make sense of the "terrible tragedy".
Speaking on the eve of a memorial service, which is due to take place today, he said: "When you live on the other side of the world, the telephone call one dreads receiving is when you are contacted to be advised of the loss of a loved one.
"When we learned of the terrible truth of my uncle's death, it became a very difficult time for all of us and for so many of his wonderful friends in trying to understand why, what purpose was there and who could do such a thing and be able to live with themselves."
The colonel, who had served in the Far East during the Second World War before working in antiques, was not known to have any enemies. While he was rarely seen in recent years walking through the picturesque village, locals portrayed him as a gentlemanly character, known as Riley, who was clearly a creature of habit.
The Oxford graduate would re-read War and Peace and the Tolkien novels once a year, while every Friday he would buy a packet of five Hamlet cigars from the local pub and a takeaway portion of fish and chips.
However, he had been devastated the previous year by the death of his wife of 38 years, Joanna, whom he had cared for devotedly after a spinal injury rendered her paraplegic in 1995.
His nephew told how Col Workman had recently started to emerge from his mourning and was even planning a holiday in Australia. "My uncle was trying to regain his purpose in his life after the recent loss of his beloved wife, Joanna, or "Nan" to us, whom he was totally devoted to caring for," said Mr Workman, who last saw his uncle during a visit last October.
"Uncle Riley spent most of his latter married life as her constant carer in their home as she became very ill and was totally dependent on him. He had been rebuilding his life since Nan passed away last year and was making plans to visit our family in Australia so he could spend some time with his only brother, along with my sister and myself, which would have been a very special time for all of us."
While detectives have managed to compile a somewhat eccentric dossier of clues, the motive appears to remain a mystery despite extensive investigations and a televised Crimewatch appeal.
What is known is that Col Workman died from a single gunshot wound. The contents of his home, including his valuable silverware collection, remained untouched. Just before 5am on the morning after the murder, a man made a 999 call to emergency services from a telephone box in the nearby village of Braughing. The caller gave an address as Hollyhock Cottage - a name that was used for the colonel's home nearly 25 years ago - before hanging up. While an ambulance went to the village, it departed soon after it was unable to find anyone in need of assistance.
It was not until the following morning that the colonel's body was discovered by his carer.
While detectives have been unable to track down the anonymous caller, they believe he has local connections, has a local accent and may be over the age of 60.
Shortly after the murder, Chris Nudds, 24, who runs a pest control business, was arrested but was released without charge.
One possible line of inquiry is that the colonel was the victim of a mistaken identity. It has been suggested that he may have been wrongly targeted because he has the same surname as a judge at Bow Street magistrates' court in London, where several suspected terrorists have appeared.
Det Supt Richard Mann, the investigating officer, whose team has spoken to every village resident over the age of 10, confirmed that the suspect was thought to be local while admitting that there were no new leads. "We still haven't ascertained any clear motive for the brutal killing," he said. "He'd have had a motive for killing Mr Workman and would have had a very good knowledge of the area and of Lt-Col Workman."
The victim's nephew paid tribute to his late uncle as he anyone who had information about the incident to come forward. "A recent Christmas function with some very close and special friends of Uncle Riley had confirmed that he was in good spirits and looking forward to the coming year and the times ahead, which have been sadly lost by the acts of a murder. We appeal to any member of the public who has heard the telephone call released by the police, made by a person who has the knowledge of this crime, to come forward and allow our family to understand some reason for this senseless act and obtain some closure for those who had the pleasure of knowing a beautiful man."