Gardai are hopeful of bringing charges in the "targeted" murder of a young man who was shot dead as he sat in the back of a car in west Dublin.
Dean Johnston (21) was gunned down just 100 metres from his home on Moorefield Avenue in Clondalkin on May 25, 2011.
Senior investigating gardai have said that the "ordinary happy-go-lucky" victim was killed over a minor local dispute.
A gangland figure believed to be involved in another murder is the prime suspect in the killing on Dean Johnston.
The thug, aged in his 20s and from Clondalkin, is also the chief suspect in the 2014 murder of Jason Carroll (38) in west Dublin.
Sources say that the gangster shot Carroll because he blamed him for attempting to murder him just five days earlier.
The known criminal, who can not be named for legal reasons, is suspected of being involved in a number of shootings.
Superintendent Dermot Mann of Lucan Garda Station said that the investigation had been very extensive, but added that gardai were interested in speaking to a number of people who were in the area when the shooting happened.
"Certainly, we believe we've done very good work from the investigation team. It has been a very extensive investigation and we just need that little bit more," Supt Mann said.
He also stated that the victim's mother, Lorraine Johnston said that her son won't rest in peace until his killer is brought to justice.
So far nine men and women have been arrested in relation to the murder. Three have been detained as potential suspects while six were arrested over withholding information.
Investigating detectives have followed more than 500 lines of inquires to date and taken 400 statements.
The weapon used, believed to be a handgun, has not yet been recovered, while the gunman is described as wearing a dark hoody, leggings and a scarf on the lower part of his face.
Supt Mann added: "There was a man walking with a dog very close to the incident and we believe he would have had to have met the gunman walking away from the scene."