Peter Reeve, who is believed to have shot dead off-duty policeman Pc Ian Dibell said "I'm sorry. I'm sorry I shot the police officer" before killing himself in a churchyard, it was reported on Sunday.
The gunman made the admission before taking his own life in a churchyard about 40 miles away from where he had gunned down Pc Ian Dibell the day before, according to the Sun.
Gardener David Colyer, 76, told the paper he was just six feet from Reeve when the fugitive shot himself in the head with a revolver, calling 999 afterwards.
"He blurted out, 'I'm Peter Reeve. I'm the man who shot the police constable in Clacton'," he told the paper.
"I realised I was standing before a killer. The man hardly paused for breath then said, 'I'm sorry. I'm sorry I shot the police officer'.
"He looked me in the eye. His voice wasn't trembling, he was calm, he was clearly trying to be sincere."
A huge police manhunt for Reeve was launched after Pc Dibell was shot dead in the seaside town of Clacton, Essex, on Monday afternoon.
Pc Dibell, 41, was off duty when he intervened last Monday in a dispute between Trevor Marshall, Mr Marshall's girlfriend and Reeve in Redbridge Road, Clacton.
Pc Dibell was shot dead, while Mr Marshall, 48, escaped with leg injuries and his girlfriend survived unscathed.
Reeve disappeared after the shooting and police launched a manhunt that lasted almost 17 hours.
His body was discovered near the rural All Saints Church in Writtle on Tuesday morning. He had dumped his car near the murder scene the previous day.
The Essex coroner's office confirmed on Friday that he had been seen shooting himself.
Reeve, reported to be a retired bus mechanic who was largely unknown to the police and did not have a firearms licence, is understood to have had several family members living near the church where he was found and may have had a relative buried there.
Pc Dibell was described by Essex Police Authority as "an extraordinary man and an exceptional police officer".
"Very experienced and respected by his colleagues, he thought nothing of going to the rescue of fellow citizens who were in mortal danger," it said in a statement.
"He was off duty at the time. He is the finest example of the deep sense of loyalty and bravery in our officers, even when not on duty, to serve and protect the public."