Colonel was blasted by 'buckshot'

Robert Workman aged 67 (left) and a recent picture of him

Detectives hunting the killer of a retired army officer have revealed he was shot with ammunition normally used to kill deer.

Lieutenant Colonel Robert Workman, 83, was shot dead on the doorstep of his own home in Furneux Pelham, Hertfordshire, on 7 January.

Police have so far drawn a blank on finding the widower's killer and turned to BBC1's Crimewatch show on Tuesday to widen their appeal for information and clues.

As part of their renewed appeal, officers revealed on Tuesday night that ballistics experts had shown Mr Workman was hit by buckshot.

Detectives said the ammunition was fired from a 12-bore shotgun and was the largest size of shot legally available.

Detective Superintendent Richard Mann, who is leading the investigation, said the ammunition was "normally used by land owners or gamekeepers for the destruction of large animals like deer."

Robert Workman aged 46 (left) and eleven years later

Police checks have found the ammunition was not available in the Furneux Pelham area and the nearest stockist was some miles away.

Detectives also used the Crimewatch program to try and trace the man who made a 999 call in the early hours of 8 January - just hours before Mr Workman's body was discovered.

The call was made in a phone box three miles away from the murder scene asking for an ambulance to attend Furneux Pelham.

A tape of the conversation between the man and the emergency services was released by police, but despite hundreds of calls from the public there had yet to be a significant breakthrough in the case.