An off-duty detective who discovered the bodies of Lesley Howell and Trevor Buchanan in a fume-filled garage raised concerns with investigating officers that their deaths were not suicide.
David Green told Coleraine Court he had suspicions that dentist Colin Howell, who 18 years later confessed to their murders, may have been involved and had alerted three detectives.
“I believed something had happened which was not good and |obviously the suspicion fell on Mr Howell,” he said.
But despite his reservations, the original police investigation in 1991 concluded that the pair had taken their own lives in a bizarre suicide pact.
That finding was based in part on the evidence of Howell and his lover Hazel Stewart, Mr Buchanan's wife, who is now on trial for the double murder.
They told detectives they believed their spouses killed themselves because they could not come to terms with their affair — when in actual fact they had |been murdered.
Mr Green was a member of the same church as the Howells and Buchanans and on the day after their murder, church elder James Flanagan approached him and said Colin Howell was worried because his wife and Mr Buchanan, also a policeman, had gone missing.
Mr Flanagan had gone to check a house in Castlerock earlier that morning at the dentist's request but had found nothing.
With Howell having rung him again to ask if he would take another look, the elder asked Mr Green, a then senior detective in the Royal Ulster Constabulary, to accompany him. This time Mr Green checked the garage of the house, which sat in a row called the Twelve Apostles, and made the grim discovery.
“I could actually see blue smoke still in the air, though it looked |as if it had been there for a while,” he said.
Mr Buchanan's lifeless body was slumped in the driver's seat of a car and Mrs Howell was lying dead in the boot surrounded by family pictures with earphones in her ears.
Mr Green, an experienced detective who at that time had been in the police for 17 years, said something told him it was not a simple suicide.
Giving evidence in the trial of Stewart, the now retired officer said he was very suspicious about how he found the bodies.
“I was just unhappy with the scene and really became suspicious about the whole thing.”
Pressed by a defence lawyer, Mr Green said “he couldn't put his finger on” exactly what troubled him about the garage.
The detective was stationed in Londonderry, but he told the court he voiced his concerns with three senior detectives from Coleraine who were working on the case.