"Lady in the Lake" killer Gordon Park took his own life in a Lancashire prison, an inquest jury has ruled.
Park was found asphyxiated in his cell more than three years ago at HMP Garth in Leyland, where he was serving a life sentence for the murder of his first wife, Carol.
The retired schoolmaster bludgeoned the 30-year-old mother-of-three to death with an ice axe in July 1976 and dumped her in the lake near the family home in Leece, near Barrow-in-Furness.
Her body had come to rest on an underwater ledge and was found by amateur divers 21 years later.
Earlier this week, his third wife, Jenny, told the hearing at Preston Coroner's Court that he "hated every minute" of his confinement and it was "a dark place for him".
Following the discovery of Carol Park's body, he was arrested and charged with murder but the case against him was dropped in January 1998 when the Crown Prosecution Service said it did not have enough evidence against him.
A second police investigation uncovered fresh evidence by linking him to the killing with the knots meticulously used to tie up the body and a piece of Westmorland green slate used to weigh it down that matched the stone used to build the family home.
The 2005 guilty verdict at Manchester Crown Court brought an end to one of Britain's most notorious unsolved murders.
Park was jailed for life to serve a minimum of 15 years but has always maintained his innocence.
In November 2008, the Court of Appeal rejected an application by Park for leave to appeal against his conviction by calling fresh expert testimony on the geological evidence heard at his trial.
His supporters have been battling to refer the case to the Criminal Cases Review Commission, which investigates possible miscarriages of justice.
Park was put on suicide watch at HMP Garth when it was said he was "very shocked" to lose his appeal.
A few months earlier he was placed on the same regime when it was discovered he had read the official report into the prison suicide of mass murderer Harold Shipman.
Mrs Park said her husband was "devastated" when his regular pastoral visits from an Evangelical church elder were stopped the month before his body was found on the morning of his 66th birthday on January 25, 2010 - also three days before the fifth anniversary of his conviction.
A fellow prisoner told the hearing he thought the visit ban was a "game changer" on top of his sentence and appeal reversal.
Prison bosses had ruled its own chaplaincy could deal with Park's pastoral needs as church elder George Harrison, from Pendlebury Evangelical Church, in Swinton - whom he met at his trial in Manchester - was not of the same denomination as previous Methodist churchgoer Park and was not local to him.
Coroner Dr James Adeley considered whether the jury could be asked to determine if the stopping of the pastoral visit had contributed to his death.
But he ruled it was not appropriate because it was uncertain when Park was told about the visit ban and it was difficult to establish whether it had any effect.
He said: "Although various witnesses have said that Gordon Park was upset at the cessation of visits there is nothing that provides the necessary causal connection to the death.
"While it may be the case that the news might have contributed to the death this is not the test and there is insufficient evidence to allow a jury to safely conclude that on the balance of probabilities the cessation of visits made more than a minimal, negligible or trivial contribution to the death of Gordon Park."