A teenager stabbed to death was on the phone when he was fatally wounded.
An inquest into the death of Reece Cullen (16) in Kilclare Crescent, Tallaght, was told a number of youths arrived at the address at 2.45pm on January 5, 2017.
Neighbour John Sutcliffe noticed the group as he worked on a car in his driveway.
"There were three or four males, all aged between 16 and 19," Mr Sutcliffe said.
Reece had been staying with friends in Kilclare Crescent since the tragic death of his mother the previous September.
"I heard only general chit-chat. There was no shouting or anything to make me look over," Mr Sutcliffe said.
Minutes later, he said, a youth came into his driveway asking for help.
"He said, 'My mate has been stabbed. Can you ring an ambulance?' His hands were covered in blood," Mr Sutcliffe said.
He phoned the emergency services then ran to the house where Reece lay injured in the hallway.
"He was lying on the ground a couple of feet inside the front door," Mr Sutcliffe told Dublin Coroner's Court.
Dublin Fire Brigade responded to a call received at 3.05pm. Paramedic Noel Keegan found Reece unresponsive.
"He was not breathing and he appeared to have a stab wound to the chest," Mr Keegan said.
The injured youth was transferred to Tallaght Hospital, where he was pronounced dead.
Pathologist Dr Linda Mulligan conducted a post-mortem and found a single stab wound had penetrated his heart.
A toxicology report found no alcohol or drugs in his system.
Gardai launched a substantial investigation, Detective Inspector John Walshe told the hearing.
"A couple of youths were at the address. One youth had arrived while Reece was on the phone and fatally stabbed," Det Insp Walshe said.
Some 110 lines of inquiry were opened, 88 statements were taken and three arrests were made.
A file was submitted to the Director of Public Prosecutions but no charges were brought. The file remains open.
Det Insp Walshe said a single perpetrator was responsible for Reece's death.
Addressing the jury of four women and four men, Coroner Dr Myra Cullinane said there was only one verdict open to them in this situation.
"The evidence, though tragic and stark, is very clear in relation to the findings you have to make," Dr Cullinane said.
The jury returned a verdict of unlawful killing by person unknown.
Speaking to the Herald after the incident in 2017, Reece's girlfriend Sophie Evans (17) described in harrowing detail how they were speaking when he was attacked.
"He was stabbed and I just heard him screaming. Then the phone went off," Sophie said at the time.
"He was just saying he was walking out the front door to come around. That's when he was struck.
"He said, 'I'm on the way down to you, baby,' then I heard him screaming, saying 'My heart, my heart'. Then that was it."
She recounted details of their relationship and recalled Reece's love of motorbikes and boxing.
"He loved his boxing, he wouldn't have been a fan of football or anything like that, but he loved his bikes and his boxing. He was very talented," she said.
The couple had been friends most of their lives but began going out around 18 months before he was killed.
"He was such a loving, caring fella. He kept to himself. He was loved by everyone. Nobody had a bad word to say about him," Sophie said.
She said Reece had been doing well after going through a difficult patch when his mother passed away, and had enrolled on a Youthreach programme.