Detectives have obtained new DNA evidence they hope may help solve the murder of a woman who was stabbed to death as she walked her dog in Cornwall 20 years ago.

Police are painstakingly tracing men who may have been on the Roseland Peninsula when Lyn Bryant was murdered, an incident room has been opened and a £10,000 reward offered for information leading to the killer’s conviction.

Bryant’s family has also launched an appeal for information and said the emergence of the forensic evidence gives them hope the mystery, which cast a shadow over the community, can be solved.

Bryant, 40, was murdered in the gateway to a field in Ruan High Lanes, the village where she had always lived, on 20 October 1998. She was stabbed with a short, sharp knife in a prolonged attack.

One of the most notable features of the crime was that four months later, Bryant’s missing tortoiseshell glasses were found lying on top of mud in the gateway. It is highly unlikely they were missed in the search of the scene and they must have been there for only a short time.

Theories include that the killer may have placed them there to taunt officers, or someone else found them and put them there but did not want to become involved in the investigation.

The spectacles remain a puzzle, but re-examination of other exhibits from the scene produced a partial DNA match for a man police suspect is the killer.

So far, no match has been found on the national police database, but officers are again tracking down men who may have been on the peninsula that day, to try to obtain fresh DNA profiles and pinpoint the killer. If new names emerge after the appeal, the profile will help eliminate or implicate them.

Bryant’s daughter, Lee Taylor, 41, said the family hoped advances in technology would help bring the killer to justice.

“I know it’s been 20 years and I’m sure people think ‘Well, what are they going to do now? It’s so long ago’, but they do now have some new forensic evidence and all they need is a name; any information that could help them in the investigation could make a real difference,” she said.

“We still need people to come forward with information to help connect the dots.”

Taylor said Bryant, a mother of two, was a lovely, kind woman who would have loved to see her four grandchildren grow up. “She loved kids. She was very family orientated. Christmas was her favourite time of year,” she said.

“She was a real homemaker. She would do anything for anyone. She was quite a quiet person, but if anyone needed anything, she would be there.”

The past 20 years have been tough for the family. “It’s been very surreal, living in a bubble, but you have to be able to kind of separate yourself from it to be able to live your life,” Taylor said.

“That [the murder] is a massive part of my life, but if I was to think about that all the time, I wouldn’t be able to go about my day to day – my job and looking after the children.

“You’d think 20 years [on], you’d kind of be used to it, but it’s still almost like a bad dream that’s just always there. You just try to remember the good times with her really, try not to dwell on the bad stuff.”

Keelan, one of Bryant’s grandchildren, who was a baby when she was killed, said: “All I’ve got is imagining what it could have been like having her there throughout my life.”

The original investigation was vast. All men and boys aged 14 to 70 living within a mile radius of the murder scene, and almost 500 men who passed within a mile of the spot that day, were traced and questioned.

More than 32,000 names are on the investigation database and Devon and Cornwall police has more than 8,000 exhibits connected to the murder.

Stuart Ellis, the force’s senior investigating officer, said: “It’s hard to imagine the toll it must have taken on the family to have lost a loved one in these circumstances but have no answers. It’s also had a profound effect on the community on Roseland and throughout Cornwall.”

On the day of the murder, Bryant had done some cleaning work at a local house, had lunch and watched Emmerdale.

Shortly after 1.30pm, she set out on her regular walk with Jay, the family’s brown and cream-coloured lurcher dog. Her body was found an hour later.