THE Boy Killers murder was caused by a row over a girl, gardai now believe. David Byrne (19) was stabbed to death after being chased by a gang of youths in Dublin.
Detectives are now probing whether a message apparently sent by Byrne to the chief suspect's girlfriend was the reason for the vicious assault.
It is understood Byrne had contacted the girl on a social networking site and that the suspect took exception to this.
The part-time DJ was knifed a number of times in the back and left to bleed to death at Emmet Court in Inchicore.
A total of 10 people -- eight of them teenagers -- have been arrested for questioning in connection with the investigation, including two 13-year-old boys. All of them have now been released.The final three men held in relation to the death were released overnight.
They included two men in their 20s who had been detained on suspicion of withholding information about Mr Byrne's death last Saturday night.
Gardai believed the men may have had information on the motive for the attack.
A 17-year-old who was detained on Tuesday for questioning was also released.
Another seven teenagers, ranging from 13 to 17 years in age, were let go from custody earlier in the week. Included among the group were two teenage girls.
Files are being prepared for the Director of Public Prosecutions.
David was well-known in the south city community where he lived and had been a regular visitor to the St John Bosco Youth Centre as a younger teenager.
He attended the centre regularly between the ages of eight and 15 and took part in drama, sport, film and music.
He had been one of a group of youngsters who had wanted to set up a community radio station, but it never got off the ground.
In 2009, his mother Ann Byrne was diagnosed with a brain tumour and Mr Byrne became her carer.
Last November, he enrolled in a six-month FAS course in personal and social employment skills working in disability.
As part of the course at the Walkinstown Association, he spent two days a week caring for adults with autism and Down Syndrome.
His project leader at the association Paul Flanagan described Mr Byrne as "always smiling" and "never in bad form".
The teenager, who had fallen into petty crime, was "doing his best to turn his life around", Mr Flanagan added.
However, his past came back to haunt him last January when he was stabbed in the neck in Drimnagh.
Mr Byrne, who lived at Davitt House in Drimnagh, admitted to Mr Flanagan that he knew who had attacked him but insisted he was safe, saying: "I'm fine."
Gardai believe they know the identity of the teenagers who chased Mr Byrne last Saturday before one of the group caught up with him and stabbed him.
A drugs debt of up to €5,000 is believed to have been the main motivation for the ambush.
In a planned attack, he was chased across a bridge over the Grand Canal and into the nearby Emmet Court complex.
Gardai and paramedics arrived at the scene just before 10.30pm and Mr Byrne was taken to St James's Hospital. However, he was pronounced dead at 11.45pm.
The incident was captured on CCTV cameras but the suspects had hidden their faces with hoods.
However, they were spotted with their hoods down on another camera later on Saturday night.
Mr Byrne had been known to associate with younger members of the 'Fat' Freddie Thompson drugs gang -- but his killing is not directly feud related.
Mr Byrne's uncle Bill Hayes described him as lovable young man trying to find work.
"David was 6ft 2ins and a lovely young fella," he said. "He was into DJing and a bit of Gaelic."
Anyone with any information on the killing is asked to contact Kilmainham Garda Station on (01) 6667300, the Garda Confidential Line on 1800 666 111 or any garda station.