Police say they may never find out how Betty died

Betty Brown

The programme featuring a reconstruction of Mrs Brown's last known whereabouts will be shown just days before the one-year anniversary of her last sighting.

The move comes as detectives admitted that forensic tests may prove inconclusive, with the official cause still listed as "unknown".

Members of Mrs Brown's family are set to give interviews to the TV programme to appeal to anyone with information to come forward and help solve the mystery of how she died.

CCTV footage of Mrs Brown taken aboard a No 3 bus in Nicolson Street will be shown to viewers, while an actress playing her will be seen during reconstructions in both the Capital and the Longtown area of Cumbria, where her body was found on January 18.

Police believe Mrs Brown caught an X95 bus from Edinburgh bus station to Longtown on Friday, May 28 last year to visit her family.

Detective Chief Inspector Jeff Ashton from Cumbria Constabulary, who is leading the inquiry, said: "The slot on Crimewatch will be on Tuesday, May 24, which is the nearest programme to the one-year anniversary of the last sighting.

"As well as camera footage from the bus, an actress will play the part of Betty in Edinburgh and down in Longtown.

"We're looking to find those people who were on the X95 bus that day and may remember Betty. Someone must've seen her, and we are hoping the programme will help us find them.

"Betty's daughter and sister will give interviews for the programme, talking about what kind of person Betty was."

In March, a team of 25 officers was deployed to travel on a Friday schedule of X95 buses between Edinburgh bus station and Carlisle.

Officers were on each of the 16 journeys to and from Carlisle during the day, speaking to anyone who got on the bus and handing out leaflets and photographs of Mrs Brown, who had been carrying two black Aldi bags on the day she vanished. Posters of Mrs Brown were put up around Longtown, which is around five miles from Gretna, where Mrs Brown's daughter Sarah lives.

DCI Ashton said: "We've had some good potential witnesses coming forward who believed they might have seen Betty. Some we had to eliminate because they had the wrong time, others may indeed have seen her.

"Unfortunately because of the state of her body, tests to establish a cause of death have been difficult. It's possible that we may never know how she died."

Mrs Brown, a 55-year-old mother of three from Gorgie, was last seen getting off the No 3 bus in Nicolson Street. Shortly before noon, cash was withdrawn from her account at the RBS ATM on Nicolson Street, which police believe was carried out by Mrs Brown.DCI Ashton has said the inquiry team were considering "every possibility from natural causes to murder" as part of the inquiry.

Dental records were used to identify Mrs Brown after the discovery of her remains by a dog walker.