The father of an engaged RAF firefighter who took his own life following a homosexual encounter said he believed "something happened" which his son "could not live with".
Oxfordshire Coroner Nicholas Gardiner today recorded a verdict of suicide into the death of senior aircraftsman Robert Fleeting, 24, who was found hanged in his room at RAF Benson, in Wallingford, Oxfordshire.
The inquest heard internal bruising, which could have been caused by a sexual encounter, was found during a post-mortem examination.
Notes written by Mr Fleeting following the sexual encounter in the early hours of September 4 last year were said to make clear he had intended to take his own life.
The court heard Mr Fleeting, who was engaged to be married, was not thought to have had a homosexual experience before that night.
Following the verdict, Mr Fleeting's father Charlie Fleeting said the family believed his death had not been investigated properly by Thames Valley Police.
He said: "I am not happy with the verdict but the coroner's hands were tied because of the evidence he was given by the police.
"The IPCC (Independent Police Complaints Commission) are hoping to get back to us because we have put in a complaint against Thames Valley Police and the way the investigation ironed itself out.
"I think something happened to my son on that night and he could not live with the fact that something happened to him, and he took his own life."
Mr Fleeting senior likened his son's case to that of Stuart Lubbock, who was found dead at the home of entertainer Michael Barrymore in 2001. Medical experts said Mr Lubbock had suffered severe internal injuries, suggesting he may have been the victim of a serious sexual assault, at an inquest in 2002.
Mr Fleeting added: "I do not believe my son did this to himself."
Robert Fleeting's body was discovered by colleagues shortly after 12.30pm on September 4 after he failed to turn up for lunch following a night out.
The inquest was told he had been out drinking with a group of friends in Henley the night before his death. They returned to the base at around 2am.
When he failed to show up later that day, his colleagues Richard Daly, Gregg Metheringham and Mark Consterdine went to look for him.
Unable to open the bedroom door, Mr Daly gave Mr Metheringham a leg up and he saw Mr Fleeting hanging from the back of the door.
Mr Gardiner was told Mr Fleeting, of Mallard Crescent, Greenhills, East Kilbride, Glasgow, had not seemed too drunk during the night out and appeared in good spirits.
But toxicology results from the post-mortem examination showed alcohol in his blood and urine which was between three to four times the drink drive limit.
Professor Ian Roberts, consultant pathologist at John Radcliffe Hospital in Oxford, who carried out the post-mortem examination, said the cause of death was asphyxiation due to hanging.
Charlotte Ward, a medic based at RAF Benson who had been out with the group, said when they returned to the barracks Mr Fleeting had become involved in a short disagreement over taxis with another colleague, referred to as Mr AB, who had also been out with them.
She told the inquest she was not under the impression Mr Fleeting was homosexual as she knew he had a girlfriend in Scotland but that, following his death, Mr AB had told her that something had happened between him and Mr Fleeting that night.
"He said they had gone back to his room, had a few drinks and that stuff had happened, that they had had sex."
Mr AB, who told the inquest he had met Mr Fleeting through training exercises at RAF Benson, said he had invited the firefighter back to his room for a few drinks and they ended up kissing and having sex.
He did not know anything about Mr Fleeting's sexual orientation and what had happened had been spontaneous, he said, adding that Mr Fleeting stayed with him until about 4.30am or 5am before returning to his own room.
Mr Gardiner asked: "When you parted company was there any sense of regret? Did he seem upset?"
Mr AB replied: "No."
The inquest was told Mr Fleeting's family had expressed doubts over whether he had written the notes found in his room but Detective Sergeant Darren Cartwright, from Thames Valley Police, said the notes and a sample of Mr Fleeting's handwriting had been sent to a forensic scientist who deduced that the notes were written by him.
Mr Gardiner said nobody would ever know what had happened between Mr Fleeting leaving Mr AB's room and the time his body was found.
"One difficulty which has been put to me is the fact there is no indication he had homosexual tendencies prior to this event," he said.
"That is one powerful argument - that he might have been distressed that a homosexual act had occurred.
"That would have been a dreadful blow to someone who was engaged to be married. I strongly suspect it was that realisation which caused him to take the action he did.
"If he did take that action, I cannot conceive it would be an accidental event given the notes that he left."
Following the inquest, Thames Valley Police Detective Chief Inspector Mark Johns said: "The coroner has returned a verdict of suicide which is consistent with our investigation into the tragic death of Robert Fleeting.
"On behalf of Thames Valley Police we would like to extend our condolences to his family."
The IPCC said it could not comment on the case.