A female relative of a man killed in relation to a land row was also threatened over the dispute.
Michael McCoy had endured a number of threats against him from the man who is suspected of killing him.
The Irish Independent has learned that the threats were linked to a row over land that the victim had with his suspected killer.
The female relative of Mr McCoy was targeted as part of the bitter dispute, which had been ongoing for some time.
Last night, sources said that gardaí were "actively investigating" the previous threats as part of their detailed probe.
Officers have not yet located the murder weapon, believed to be a wooden implement, that was used in the fatal assault and are carrying out detailed forensic examinations.
A man was questioned by gardaí over the weekend in relation to the death, but was released without charge on Sunday night. A file is being prepared for the DPP.
The 64-year-old victim lived in Ballinascorney Upper, Brittas, Co Dublin and was a passionate conservationist.
Last night, Ian Lumley of An Taisce paid tribute to him.
He said people of his kind were few and far between and very much needed and appreciated around Ireland.
"I would have had extensive contact with Michael over the years and I had great respect for him," Mr Lumley said.
"He will be an immediate loss. He was somebody - and we have people like him in other parts of the country - who was needed; people who take special interest in the protection of their area.
"An Taisce would have considered him to be a great public interest campaigner," he added.
Mr McCoy's body was found on Ballinascorney Hill in the early hours of Friday on a mountain path after an extensive search.
It is believed he left his home to walk his two boxer dogs early on Thursday morning and failed to return home.
One of the victim's dogs, Fia, is still missing since the incident.
Mr McCoy's daughter, Rachel posted a message online yesterday asking for support in the family's campaign to locate the missing pet.
"Please can you shout out for our #findfia campaign," she said.
"Sighting on the Ballinascorney Road, if people can keep an eye there," she added.