A heartbroken mother has appealed for anyone who knows anything about the brutal murder of her son to speak out and help end her family's agony.
Paul Byrne (20) disappeared on July 15, 2009, after he got into a car with two men outside his house.
One of the passengers in the car was a notorious gangster who is now on the run from jail.
Mr Byrne's skeletal remains were found over a year later in a remote forest about 11km from Blessington, Co Wicklow, and the case has been the focus of a murder investigation since.
The first major breakthrough happened in the probe earlier this month, when a 22-year-old Tallaght man was arrested and questioned about his knowledge of the murder.
He was released from Bray Garda Station without charge. A file will now be prepared for the DPP as gardai continue to hunt for the chief suspect who is believed to be based in the UK.
Mr Byrne's mother, Ashely Dempsey, told the Herald that she welcomed the arrest, but she is disappointed that there were no further arrests or criminal charges in the long-running case.
"I would like to thank the police for their ongoing work in the case, but there are loads of people out there who know what happened to my son, but they won't say anything.
"I am appealing for these people to come forward even at this stage, after the sixth anniversary of Paul's murder," Ms Dempsey said.
When asked what she thinks of the criminals who murdered her son, Ms Dempsey said: "They disgust me, they are the scum of the earth. The effect that this has had on my family has been horrendous and the pain of it will never go away.
"At this stage, all I want is closure and that means that those responsible be brought to justice.
"My son was killed without ever getting to meet his daughter."
Paul's partner, Martina McQuillan, had only found out she was pregnant with their second child in the weeks before Paul went missing. She gave birth to their second daughter, Faith, in February 2010.
Sources say that Mr Byrne, from Kilmartan Green in Tallaght, was murdered by the same criminal gang connected with on-the-run Tallaght thug John Paul Duncan.
Duncan (30) simply walked out of Loughan House in Cavan last February, just two days after he was moved to the facility from Castlerea Prison.
The convicted drug dealer, who was sentenced to eight years in May 2010, has two more years left on his sentence for possession of almost €3m worth of drugs.
The same gang murdered drug dealer Stephen O'Halloran, who died in a hail of bullets while sitting in a parked car outside his home in January 2009.
David Patchell of Rossfield Crescent, Tallaght, was convicted of the murder in April, 2011.
His trial heard that he was one of two gunmen who fired 10 bullets at the parked car where O'Halloran and two other men sat drinking and smoking cannabis. The prosecution described it as a "slaughter pen".
The other gun killer has never been caught.
It emerged during Patchell's murder trial that he was friends with Paul Byrne, who was also interviewed about the shooting.
However, Paul's mother said her son was not with Patchell on the night of the shooting and the two were not best friends.