Gardaí from the cold case unit have launched an investigation into a "contract to kill" attack on a chronically ill man in Dublin 22 years ago.

Two men were jailed for their role in the 1988 attack but said the dead man's wife and daughter offered them £3,000 to murder him.

It is understood the cold case team of detectives, led by detective superintendent Christy Mangan, will re-examine every aspect of the case and attempt to bring more charges against others who may have been involved in the attack.

In May 1988, four men broke into the home of Christopher Payne (52) of Rutland Grove in Crumlin. Jessie O'Dwyer (19) of Saul Park, Crumlin, and Stephen McKeever (18) of Dromard Road in Drimnagh, attacked Payne with a hammer and a hatchet, inflicting serious head injuries.

Payne, who suffered from a chronic kidney ailment, was left "like a vegetable" after the assault and died six months later. However, no pathologist could say his death was directly linked to the beating.

During their trial at the Central Criminal Court in 1989, Justice Henry Barron accepted that the two teenagers were offered £3,000 by Sharon Payne (15,) and her mother Philomena, to break into their home and kill him but to make it look like a botched robbery.

O'Dwyer was Sharon's boyfriend at the time. The two men admitted they were party to a "contract to kill" and were sentenced to nine-and-a-half years each.

Philomena Payne and her daughter were arrested in connection with the attack on Christopher Payne shortly after his death but were not charged. The two women's whereabouts are unknown.

Two other teenagers who broke into the Payne family home but did not take part in the attack were given suspended sentences for burglary.

Stephen McKeever told gardaí that his 15-year-old girlfriend asked him and Jessie O'Dwyer to kill her father and said they would be paid £3,000 from an insurance policy. When they broke in, they tied up Sharon and Christopher Payne junior and when Philomena Payne came home, she was also tied up. When Christopher Payne senior came home, he was bundled into another room.

McKeever said O'Dwyer told the man: "We don't want your money. We want your life." His statement added: "I hit him over the head with the hatchet. Jessie hit him with the hammer."