A 16-year-old boy who kicked a man to death has been described as being like a "powder keg waiting to explode" because of years of deprivation and abandonment in his home life.

The teenager was in the care of the State when he murdered 39-year-old Claudiu Robu, just hours after he had assaulted Mr Robu and robbed his phone.

The Central Criminal Court heard the youth had gone back to find Mr Robu lying in the lane where he had earlier robbed him, and repeatedly kicked and stamped on his head while watched by another youth.

The other boy reported the murder to gardaí and the teen was arrested and later pleaded guilty.

At a sentence hearing today, the court heard that Claudiu Robu died "a horrible and lonely death in a back lane" in the early hours of 14 September last year.

He had been living with a friend, had fallen on hard times and had some difficulties with alcohol. He had been drinking that day when he encountered the teenager, who took him down a laneway off Madison Road, South Circular Road in Dublin 8.

The teen assaulted him and took his phone before returning to his care home later that night and telling another boy what he had done.

He asked the other boy to accompany him to the shop and then took him to the laneway, where the boy witnessed him stamping on Mr Robu as he lay on the ground.

The youth said they returned to the care home where care staff saw him wash his runners.

The other youth said he was shocked and sickened by what he had seen and he ran back out to a garda station to report it. He took gardaí to the scene, where they found Mr Robu seriously injured and gasping for air. He died at the scene as emergency services were treating him.

A post mortem showed he had died from severe blunt force trauma to his head. The injuries sustained were from a "high velocity" force often seen in road accidents.

In a victim impact statement read to the court, his family, who live in Romania, described the trauma they suffered after hearing how he had died.

His brother said he was also working in Ireland at the time and became too afraid to live here after the murder. He said their mother suffered shock and depression and they would never get over the "pain in their souls".

The victim's wife and two children could not accept that he was no longer with them.

After his arrest, the youth tried to blame the boy who had reported the killing, telling gardaí he was "off his head" at the time. He said he was pissed off about being in care and at his family situation. His father had died when he was young and his mother had left the country, leaving him to live with his step father who had assaulted him, resulting in him being taken into care just months before the murder.

Defence Counsel Brendan Grehan read a letter from the boy, which read: "Dear Judge, I am very sorry for what I have done and I know what it is like to lose someone in your family. I know what his family is going through.

"I feel guilty and this will stay with me for the rest of my life. If I could turn back time this would never have happened.

"My time in detention has given me a chance to look back over my behaviour and change."

A probation report described the boy as being incredulous that he could have caused so much harm to another person that he had died from his injuries.

The deceased man was intoxicated and would not have been able to defend himself.

The court heard the boy came to Ireland from Eastern Europe as a very young child. His mother had remarried, but later left and he remained with his step father. Their relationship was not good, resulting in him being taken into care after being assaulted by his father.

He had resided in a number of different foster homes over a short period of time in the run up to the murder.

He was diagnosed with ADHD as a child and had been taking medication for this and attending a clinic, but his stepfather had not been taking him to his appointments.

He was described as being unable to use language to express emotions or identify a multitude of emotions he had suppressed over 17 years of neglect.

He had never experienced a nurturing home, had been removed from an abusive home and did not have the social or verbal skills to navigate his new environment in care.

The report describes him as being unable to articulate the loss, loneliness and numerous rejections he had experienced, and the only expression he knew was anger.

His own phone stolen from him in the run up to the incident, and he was "almost like a powder keg waiting to explode", Defence Counsel Brendan Grehan said.

He said the boy would need intervention and therapy to deal with anger, and was coming to terms with what he had done.

He said he was in the care of the State and was intoxicated and abusing various drugs at the time.

He will be sentenced next month.

The mandatory life sentence, which applies in the case of an adult, does not apply to juvenile murderers.

The judge said a judgment on sentencing of juveniles is awaited from the Court of Appeal, and it would make sense to wait for that judgment before passing sentence in this case.