Detectives investigating the murder of a retired army colonel shot dead at his Hertfordshire home are to use a dialect coach to try to catch his killer.
The man called an ambulance to Col Workman's cottage
The expert has been given a recording of a 999 call asking for a crew to attend the home of 83 year old Robert "Riley" Workman.
The anonymous caller, who used a public phone box, hung up after 20 seconds, following the killing in January.
Detectives still believe the Colonel's killer was a local man.
Mr Workman, a widower, was shot by a shotgun at point blank range in the doorway of his cottage in Furneux Pelham on 7 January.
Early the following morning, a man phoned 999 from a phone kiosk in the nearby village of Braughing and asked for an ambulance at Hollyhock Cottage.
The cottage, in The Causeway, had not been called by that name for 24 years. The colonel and his wife Joanne had re-named their home Cock House.
Lt Col Robert "Riley" Workman was found by his carer
Det Superintendent Richard Mann, who previously headed the enquiry, said the caller pronounced the village's name in the local way. He said: "I think it does point to someone with local connections."
He said the man had a 'rural traditional and local accent', and voice experts believe him to be older than 50.
On Monday, a Hertfordshire Police spokesperson said: "we are speaking to a dialect coach."
They hope the coach will help them focus their efforts, and they are also working on a chronological breakdown of Mr Workman's life to find out more about his acquaintances.
Last month, it was announced police had arrested a man eight weeks earlier. He was questioned and remains on bail.
At the time, police said the man had been arrested for failing to provide officers with a sample of his voice to analyse.