A council leader and former mayor abused his wife behind closed doors for almost a decade before laying out wills and funeral instructions, then luring her to her death.
Keith Johnson, 58, shot his wife Andrea, 44, dead outside their home in Compit Hills, near Cromer, Norfolk, before turning the gun on himself on December 2.
Following an inquest at Norfolk Coroner's Court, a domestic violence homicide review was published detailing how the leader of North Norfolk District Council abused his wife. Police and health professionals had not been aware of the violence, which came to light in a diary found after Mrs Johnson's death.
On the day of the murders, Mr Johnson armed himself with his wife's shotgun and invited her back to their bungalow, promising he would not harm her, the inquest heard. Coroner William Armstrong concluded that Mrs Johnson suffered an unlawful death while Mr Johnson killed himself. He said: "These deaths could not have been foreseen by the police, by medical professionals or anybody else concerned."
Mr Armstrong said: "The killing of Andrea by Keith was not committed in a moment of madness or while his ability to control his actions was impaired. The killing was deliberate. He made a decision to kill Andrea and then to kill himself."
Gaynor Mears, who wrote the report, said the case highlighted that domestic violence existed within all social classes and said people should not be blinded by a person's public image. She told the inquest: "It happens in urban areas, rural areas and across all social stratas."
The couple, who had no children, had been together for almost 20 years and married in 2004. They were in an open relationship, with both having affairs. The inquest heard Mr Johnson threw customer services worker Mrs Johnson out of their bungalow the previous night because he felt she was impeding his career.
He invited her back the next day with the promise that he would not be violent. He was waiting for her with a shotgun and police found a series of notes, including details of how to dispose of the estate and how the couple should be buried, suggesting he had planned the murder.
Detective Sergeant Paul Brownsell said Mr Johnson had apparently prepared for the murder by taking the shotgun, legally held by his wife for clay pigeon shooting, from its cabinet. He said: "Earlier that morning he settled a paper bill, went to see his mother and got out various wills and wrote various notes which were left on display on a kitchen worktop. He was usually gregarious and larger than life but, from our investigations, it would appear that he was subdued and not himself."
Outside the inquest, Mrs Johnson's parents, Jan and John Chadwick, described her as a "beautiful, loving and bubbly character". They added: "We feel for Keith's family, as they are victims too."