Peter Reeve's body was found with head wounds and a weapon nearby, The Daily Telegraph reported.
Police had been searching for Reeve after Constable Ian Dibell was shot and killed in the street in Clacton-on-Sea in Essex Monday.
Jim Barker-McCardle, Essex Police chief constable, said police were alerted to the body and its location by a citizen.
"I can confirm Peter Reeve, the man wanted for the murder of a serving police officer, was found dead, with a weapon in a Writtle churchyard and no shots were fired by the police," Barker-McCardle said during a briefing.
Reeve, 64, was "largely unknown" to the police before Monday and did not have a gun permit, police said.
Dibell was shot after he rushed out of his house to subdue an armed neighbor who reportedly opened fire during a fight about noise and parking, the Telegraph.
"Everyone will think there must have been some sort of catalyst that prompted a set of events of this magnitude and this scale of tragedy," Baker-McCardle said.
A statement read on behalf of Dibell's family said the police officer was "a hero. He has paid for the act in the most devastating way. He will be deeply missed and no words can describe the loss."
Home Secretary Theresa May offered "sincere regret" to Barker-McCardle, Sky News said.
"Our police officers keep us safe day in and day out and sadly PC Ian Dibell has paid the ultimate price."
Douglas Carswell, a lawmaker from Clacton-on-Sea, said, "This is not Los Angeles or urban London. This is Clacton and I think people will be truly shocked and appalled."