A vile rapist was strangled in Glasnevin Cemetery, chopped up and buried in a Dublin park, gardai believe.
A dig will begin in the coming weeks for body parts of James Nolan, whose arm washed up on Dollymount Strand in 2011.
It is believed Nolan, from Finglas, was strangled to death by his killer in Glasnevin Cemetery before his body was brought to an address in north Dublin and cut into pieces.
Details of the dig for some of the scattered body parts in a park on the northside comes as gardai in Co Monaghan also plan to resume searches for other remains of the convicted sex offender.
Officers are carrying out fresh investigations because of details left in a 21-page suicide letter written by Nolan's killer and sent to family members.
After dismembering the body, the killer then disposed of most of Nolan's body parts in Co Monaghan and at a park that is "extremely popular" with walkers on the capital's northside.
It is understood that the severed arm that was found washed up at Dollymount Strand had been thrown into the Tolka River and then washed out to sea.
Gardai are treating the contents of the letter as being "very credible". Its now-deceased author was a very close associate of Nolan and is the chief suspect in the shocking case.
Detectives are working on the theory that after being strangled to death, Nolan's body was dismembered, he was decapitated and even his fingers were cut-off.
An inquest previously heard that the rapist's arm was found by a man walking his dog on February 8, 2011.
State Pathologist Dr Marie Cassidy said that Nolan's arm was "cleanly" severed post-death using a very sharp knife and tattoos had been cut from the skin.
Nolan's last known whereabouts were when he collected methadone from the Wellmount Clinic in Finglas on November 30, 2010.
Nolan had been missing since shortly after he was released from Portlaoise Prison having served a three-year sentence there for burglary in Booterstown, south Dublin, in 2005.
In 1986 he was jailed for 14 years when he was convicted of rape and false imprisonment.
The 1986 rape attack is considered one of the most savage to have ever happened in Ireland and the victim was brutally attacked in front of her partner.
Sources say that the rape incident is being probed as a possible motive for Nolan's gruesome murder even though his suspected killer was not present on the night.
"One theory coming from the suicide letter is that Nolan's killer murdered him because he was absolutely disgusted about the rape but there are other theories as well," a source said.
These include reports that James Nolan received a cash windfall after his release from prison but he refused to help out his killer financially and a major row occurred.
Another prominent theory being investigated is that Nolan had been stealing money from an elderly woman known to both of them.
Earlier this month it emerged that gardai in Co Monaghan spent two days searching a lake in the county after a relative of Nolan's passed on the suicide letter to gardai.
In the letter, the man is believed to have described butchering Nolan before dumping some of his remains in Lough na Glack lake near Carrickmacross.
Gardai believe the letter's author became concerned after a search was carried out in the lake for the remains of a Polish national the previous week.
He took his own life after writing the shocking letter.
At the inquest into Nolan's death, evidence of how he was identified was given by a senior garda.
Detective Inspector Paul Scott revealed that his identification was confirmed using a DNA sample taken from the arm which matched a DNA profile on a UK police database.
Nolan had been arrested at Holyhead in 2004 when he was found using a forged driving licence and details and DNA were taken at the time.
The photograph and fingerprints were also cross-referenced with the Garda database.
Det-Insp Scott said the Garda diving unit had carried out an extensive search of the sea around Dollymount Strand, but had found nothing else.
Professor Marie Cassidy said there was no evidence of any bleeding or blood loss into the tissues, indicating that he was dead when the cuts were made.
The limb had been in the water for days "if not weeks", said Professor Cassidy.
Nolan's arm had been "fairly cleanly cut", using a "very sharp implement".
"A propeller can leave quite a clean mark on a body, but they are usually longer. These were very carefully and deliberately going around the whole circumference of the limb. It was deliberately cut," she said.
Two large sections of skin had been removed from the victim's upper arm and forearm, with the cuts "cleanly excised".
Sources say that an exact date for the planned dig in the north Dublin park has not yet been finalised but should happen "sooner rather than later".
"It is not the best weather at the moment for this kind of operation and the terrain in the area is difficult enough," a source said.
"Another issue is that the park will have to be closed off to the public while this is going on and it is an area that is very popular with walkers.
"It is hoped the dig will happen within the coming weeks."