A pair of cigarette butts have provided crucial DNA evidence that could free a man who has spent the past 16 years in jail for a murder he has always claimed he did not commit.
The police are also thought to have uncovered evidence that points towards a new suspect for the killing of Arthur Eathorne, 74, who was bludgeoned to death in his flat in Plymouth in 1990.
The Criminal Cases Review Commission (CCRC), the body that investigates potential miscarriages of justice, is understood to be on the verge of announcing that the man convicted of the murder - 42-year-old Robert Kennedy - should have his case re-examined by the Court of Appeal.
Kennedy, who has been behind bars since 8 October 1990, is at Garth prison in Preston, where he is on suicide watch.
His lawyer claims that his case hinges on new DNA evidence, two disputed cell confessions, and fingerprint evidence that points towards a murder suspect.
He said the conviction and failure to clear his name may also be as a result of homophobia and a climate of fear among the gay community in the South-west during the early 1990s.
A murder inquiry was set up after Mr Eathorne was found beaten to death at his flat in Holyrood Place on 18 September 1990.
The pensioner, who was well known in the gay community and had a number of young men visiting his flat for sex, sometimes allegedly for cash, was struck on the head, possibly with an ashtray.
Kennedy was arrested 20 days later and subsequently charged with the killing.
At the time of the murder, DNA technology was in its infancy. Among the exhibits seized were two cigarette butts left by what police describe as a "non-secretor" - a person whose blood type does not show up in other bodily fluids such as saliva.
Kennedy, then aged 27, was found to be a "non-secretor" - along with 25 per cent of the population - which the prosecution implied placed the suspect at the scene of the murder.
The prosecution's evidence also included an alleged confession that Kennedy had made to an inmate in Exeter Prison.
In December 1991, Kennedy, who was bisexual, was found guilty by an 11-1 majority verdict at Plymouth Crown Court.
In 2002, the CCRC began to reinvestigate the case and, in 2005, asked Devon and Cornwall Police to reopen the inquiry.
The new investigation made several startling discoveries. Forensic analysis was able to recover DNA from the two mystery cigarette butts - which proved that neither belonged to Kennedy.
The police admitted that the two DNA profiles - which have never been identified - indicated that there may have been at least two other people in the flat shortly before Mr Eathorne's murder.
The police have also conceded that because of Mr Eathorne's lifestyle, witnesses at the time may have been too "fearful or embarrassed" to come forward with information.
It looks likely that the CCRC will refer the case to the Court of Appeal in the next few weeks. The case would then be quashed, upheld, or a retrial ordered.
Kennedy is becoming increasingly depressed, it seems. In a letter to his solicitor, Maslen Merchant, said: "I do not know how much more I can handle or take. I have done 16 years now for a crime I did not commit. I'm finding it harder and harder as each and every day goes by."
Mr Merchant added: "Bob Kennedy has not protested on the prison roof, or campaigned or written letters. He has just sat quietly for the past 16 years in jail saying he did not commit this murder.
"Imagine being locked up for nearly 17 years for a murder you did not do. The ramifications for your mental health and your family are horrendous."
A CCRC statement said: "We cannot comment on the detail of individual cases. However, this has been a complex and lengthy review and we would hope to be in a position to make a decision before too long."Reuse content