A DEVASTATED father has spoken of his horror after he discovered his son's lifeless body on the side of the street less than 100 yards from the family home.
A second man, Sean Turner (22), an accomplished professional boxer, was also stabbed in the same incident, and remains in St Vincent's Hospital with serious internal injuries. The stabbings are understood to have occurred after a row over an alleged €50 debt.
A man in his 30s has since been arrested and is being detained at Shankill garda station under Section 4 of the Criminal Justice Act 1984.
David had been enjoying a seasonal get-together with old friends in his parents house at Rathsallagh Park in Shankill, south Co Dublin, when shortly after 5.15am one of his friends received a text message to say Sean Turner had been attacked.
It was believed the man who has been arrested had earlier been involved in an argument at the party with another man, who was known to Mr Turner, regarding an alleged €50 debt.
It is understood the man in his 30s left the party. The stabbing of the two victims took place sometime later.
"David and another friend opened the front door and walked outside to see if the guy was all right. They went the wrong way, but then David saw his friend on the ground," David Snr told the Irish Independent.
"He ran after the guy he thought had carried out the attack. David's friend was helping Sean on the ground.
"But while he was helping Sean, he looked over and then saw David lying on the ground."
He said one of David's friends then ran back to the house to raise the alarm. Another friend then ran upstairs to the parents bedroom to tell David Snr and his wife, Iris, who were asleep, that their son had been stabbed.
"There were still two or three in the house downstairs at that stage and they didn't have a clue what had happened outside until someone ran back and told them," he said.
"The party had practically broken up before it happened.
"I ran outside and around the corner and my wife ran out after me. One of the other lads, Darren, was holding David down to try and keep in the blood.
"It didn't even register with me that another lad had been stabbed. He told me to go and see if Sean was alright. As far as I know they'll know in 48 hours if he'll pull through."
He added: "We're all devastated and shocked. I'm still dressed in the clothes I got out of bed in this morning. The whole thing is just unbelievable."
Emergency service personnel made frantic attempts to save the lives of both men before they were rushed to St Vincents Hospital, where David was pronounced dead shortly after 8am.
The scene was sealed off yesterday pending a full technical examination by the Garda Technical Bureau.
In a tragic twist, Mr Spain had been friends with David Greene (pictured), an Irishman who was murdered in Australia in 2012.
The 30-year-old from Cabinteely was staying at a backpacker hostel in St Kilda East, Melbourne, when he was attacked and killed by Luke Wentholt (32).
Wentholt was later jailed for 18 years. Greene had previously gone to school with Tom Meagher -- his wife Jill was raped and murdered by Adrian Bayley in Melbourne last year.
Mark O'Regan and Ken Foy