The family of an 83-year-old dog walker "brutally" stabbed to death have described him as "immensely kind".
Peter Wrighton's body was found on Saturday near Fiveways Junction, three miles south of East Harling in Norfolk.
He was repeatedly stabbed in his neck and head, post-mortem examination tests showed. The murder weapon has not yet been found.
Norfolk Police said it was not yet known if retired BT worker Mr Wrighton, from Banham, knew his killer.
Officers said they had received more than 100 calls in the past three days about the murder.
Mr Wrighton, a married father-of-two and grandfather, has been described as "gentle" and "mild mannered".
In a statement, his wife of 59 years and family said: "Peter was immensely kind and never had a bad word to say about anybody and people always seemed to take a liking to him.
"We are extremely thankful for all the people who have come forward to speak with the police and hope we will soon be able to understand why this has happened."
Mr Wrighton had volunteered at Snetterton Dogs Trust and Bressingham Steam Museum as a guard on the trains.
The dogs trust said his murder was a "devastating situation".
Phil Moore, parish secretary at the St Mary the Virgin church in Banham, who knew Mr Wrighton, said: "He was a very nice man, a very gentle man. He would stop and have a chat. He loved his dogs and loved his family. He never had a bad word to say about anybody.
"I am very sad. It will be a shock not to see him around the village."
Alastair Baker, from the steam museum, added: "We were already shocked that something had happened so locally but to find out it involved Peter is even more shocking.
"He was a kind, gentle guy who everybody liked. Our thoughts are with his family who must be devastated."
Mr Wrighton's body was found at about 10:45 BST on Saturday.
Norfolk Constabulary has about 50 officers working on the murder case.
The force has asked people who live within five miles (8km) of the scene to check their bins for "a weapon or anything unusual".
Ch Supt Mike Fawcett said: "It's unusual to have an attack where we can't show if there's any connection between the victim and the offender, and we don't know the motive for the attack."
He added: "If the victim is not known to the attacker, it is really strange for somebody to just attack somebody in the open.
"We have somebody who is violent out there and it's somebody we need to find quick."
He said if someone is "protecting somebody" they should consider the victim of the crime.
Police said there was no indication Mr Wrighton had been killed in a robbery.
A 71-year-old woman was raped at West Harling heath in 1994, close to the location of Saturday's murder. The attacker in that case was never identified.