A Sandhurst instructor yesterday admitted killing a police constable by pulling on a patrol car handbrake as they travelled at 70mph.
Staff Sergeant Steven Graham, 40, was being taken to police cells after he was arrested during a drink-fuelled "domestic incident".
Pc Joe Carroll, 46, was driving accompanied by an inspector, when Graham grabbed the brake, causing the vehicle to skid and overturn.
It was an apparent attempt by Graham to stop the car and escape from custody.
Pc Carroll died in the crash on the A69 near Corbridge, Northumberland. His colleague, Insp Brian English, survived.
Graham pleaded guilty to manslaughter when he appeared at Newcastle Crown Court, but denied assaulting Insp English. That charge was allowed to lie on file.
Richard Bloomfield, defending, asked for psychiatric reports to be prepared before sentence because Graham had suffered trauma during his 22 years in the Army.
Mr Bloomfield said: "During the course of his career he was in the frontline artillery in the first Gulf war.
"He served in Bosnia and Kosovo and served two terms in Northern Ireland."
Graham's girlfriend at the time of his arrest told police she was concerned the Army was not providing him with enough support. His service record showed he had had drink problems.
Kingsley Highland, prosecuting, said there were few sentencing precedents.
"Almost exclusively [in] charges of manslaughter where a motor vehicle is used, the defendant has been behind the wheel of the car," he said. Mr Highland added that the defendant had entered a guilty plea at the earliest possible opportunity and should be given credit for that.
Judge David Hodson adjourned the case until the week beginning July 31, saying a prison sentence was inevitable. He remanded Graham in custody.
Graham was arrested for breach of the peace when he was taken away from a house in the Hexham area at 2.30am in April. Because there were no cells at Hexham, he was being taken to Etal Lane police station in Newcastle when the incident happened.
At the time he was an instructor teaching officer recruits short courses in communications at the Sandhurst Military Academy.
A Ministry of Defence spokesman said: "Sgt Graham had nothing to do with Princes William or Harry. He was not their instructor." His future within the military will be determined by his CO when the case is concluded.
Pc Carroll, 46, was described as a "good old-fashioned copper". He was stationed at Bellingham, Northumberland, and had worked as a community officer for 13 years.
He and his wife Caroline, also 46, a teacher, had no children and lived in West Woodburn. They met at a church in South Shields when they were both students at Sunderland Polytechnic where he was taking an engineering degree and she was studying to become a teacher.
Mrs Carroll said yesterday: "Joe, my vibrant and fun-loving husband was killed because of a selfish act.
"Steven Graham was thoughtless and foolish. He did not think of the consequences of his actions. He now has time to contemplate the error of this. My hopes, dreams and plans for the future died with Joe. I am slowly re-forming my life."
Pc Carroll's funeral was conducted by the priest who officiated at their wedding 21 years earlier and was a friend of the couple.
Father Harry O'Rielly, who came out of retirement for the occasion, said: "He became less comfortable with much of the police work as the years went by, including night duty, which ironically led to his death." Pc Carroll, whose hobbies included hiking and rowing, was born in Batley, West Yorks, and is survived by his mother Hilda and two sisters, Mary and Trish.
Mike Craik, the Chief Constable of Northumbria, spoke of Pc Carroll's "massive personal contribution" to the force and community. He said: "He knew everyone and everyone knew him. He was a real old-fashioned copper. That is why he was out there at 2.30 in the morning."