The human remains were discovered by Gardaí during a search at a site in County Monaghan as part of an ongoing investigation into the death of James Nolan.
The discovery was made at Lough Na Glack near Carrickmacross this afternoon, a spokesperson said. Searches at the site have been ongoing since 6 June after his torso was found last month. The local Coroner and the State Pathologist have been notified.
The remains have yet to be identified and enquiries are ongoing. Searches at the site are continuing and no further information is available at this time, the spokesperson added.
Searches were launched several months ago following revelations from a suicide letter written by Nolan’s brother, Thomas, who has since taken his own life. In the 21 page letter, which was sent to family members, Thomas Nolan claimed responsibility for his death.
Reports last week suggested the Gardai were scouring the lake for Nolan's severed head.
"The information that gardai received indicates that Nolan's head may be at the Co Monaghan location.
"This is a live murder investigation," a senior source told the Herald.
A "mainly intact" torso was discovered about 1ft beneath the ground in Tolka Valley Park on April 10. Sources say that the torso discovery was made at almost exactly the same location described in the lengthy letter left behind by Thomas.
The letter states Nolan was strangled to death in Glasnevin Cemetery. His body was then taken to an address in north Dublin and cut into pieces. The killer disposed of most of Nolan's body parts in Co Monaghan and at Tolka Valley Park.
It is understood that Nolan's severed arm, found washed up at Dollymount Strand, had been thrown into the Tolka River and then flowed out to sea. Detectives are working on the theory that after being strangled to death by the man known to him, his body was dismembered, he was decapitated and his fingers were cut off.
In 1986, Nolan was jailed for 14 years when he was convicted of rape and false imprisonment. The rape is considered one of the most savage to ever happen in Ireland and the victim was brutally attacked in front of her partner.