An "extremely violent and chaotic" 16-year-old who it is believed jumped on the head of a vulnerable homeless man who later died is a suspect in another assault that took place less than 24 hours earlier.
Gardaí have launched a murder inquiry into the attack, which happened in a laneway off Madison Road, Kilmain- ham, at around 1.30am yesterday after the victim's mobile phone was stolen.
The only suspect in the case was being held last night at Kevin Street garda station.
The Herald can reveal that officers are also investigating if he is linked to another brutal assault in the north inner city at 4.30am on Sunday, which led to a man suffering potentially life-altering injuries.
In addition, he is being investigated by Pearse Street gardaí in connection with a mugging in the St Stephen's Green area on September 4.
"Yesterday morning, the suspect is understood to have first beaten up the victim and then stolen his phone before coming back and giving the poor man an absolute hiding," a senior source said.
"He jumped on the victim's head in the presence of his friend, who has given a full statement to gardaí.
"However, the friend's clothes have also been seized to be examined as a precaution. The friend is not a suspect at this time."
The "out-of-control" 16-year-old, who is well-known to gardaí, is originally from Slovakia.
The victim was aged in his 40s and believed to be originally from Romania.
He had been sleeping rough and previously had an address on the capital's northside.
Gardaí were alerted to the assault only minutes after it happened when a friend of the suspect, who told gardaí he had witnessed the violence, notified staff in the hostel where they live.
When gardaí arrived at the south city laneway, officers arrested the teenage suspect while the victim was still alive.
However, he died from "catastrophic head injuries" a short time later.
"The level of violence used against this vulnerable man was shocking," the source said.
"The suspect in the case is a very violent individual and gardaí believe he is responsible for another assault in the city over the weekend, which has left a man in a very bad way.
"It is suspected that he was on some kind of rampage, and if everything stacks up it is highly disturbing to think that he brought another person back to watch him jumping on the victim's head."
CCTV will play an important part in the investigation into the killing.
It is not known when the teenager, who was supposed to be observing a nightly curfew, or the dead man first came to Ireland.
Tony Walsh, of the Feed Our Homeless charity, commented on the brutal murder on the organisation's Facebook page yesterday.
"This is very sad news to hear this morning. This man was known to our Outreach Support Team. He was a very kind and also respectful man," he wrote.
Neighbours on Madison and Mayfield Roads were shocked to wake up yesterday to find gardaí on the street and the lane sealed off.
"I hardly slept after the emergency services and gardaí arrived in the early hours," said one woman on Madison Road.
Another left a small bunch of flowers from her garden at the scene.
"I don't know who the poor man is, but he is part of somebody's family somewhere," she said.