Mr Alan Byrne, who was shot and seriously injured in Dublin's south inner city yesterday morning, was with Mr Josey Dwyer, a heroin addict and AIDS sufferer, when Mr Dwyer was beaten to death by a mob nearly three years ago.
The men were close friends, and Mr Byrne later spoke out against his killers. Mr Byrne has since managed to give up his own heroin addiction and has been working full-time as a warehouse-man in Walkinstown.
Garda sources suspect Mr Byrne was shot because he was co-operating with gardai investigating his friend's killing.
At the time of Mr Dwyer's death it was learned that at an IRA meeting in the Liberties it had been decided to step up republican involvement in community activity against suspected drug dealers. Within a few days Mr Dwyer, a known heroin addict in the advanced stages of AIDS-related illness, was beaten by a mob. He weighed only six stone and succumbed quickly to internal injuries from being kicked in the chest when he was on the ground.
While he was dying he warned local children to stay away from him because he was concerned they would be infected with his blood. He was reported as having shouted: "Keep away from me, girls. I've got AIDS."
After press reports linking the IRA to the anti-drugs activity in the south inner city, it is believed the republicans withdrew from involvement in violence against suspected dealers for a time.
However, gardai say the local IRA has again returned to anti-drugs activity and has been involved in shootings and intimidation.
There are suspicions that republicans were responsible for the murder of a man from the north inner city who gardai believe was a minor drug dealer. Mr Gerard Moran (35) had previously been involved in fights with anti-drug campaigners.
Mr Moran was shot in the thigh with a shotgun when he was delivering Chinese food in Drumcondra last November. His killer may have intended only to seriously injure him by shooting him in the leg, but the blast severed a main artery and he died from blood loss and shock.
Gardai also believe IRA members were behind other shootings and widespread intimidation of suspected drug dealers in Dublin's inner city last year.
Republican gunmen are thought to have carried out two attacks in the Crumlin area, when gunshots were fired through the front doors and windows of two houses within a short period at Downpatrick Road and Sundrive Road on one evening last July. No one was injured.
Local Garda sources say there has been considerable involvement in the "anti-drug" movement in the south inner city in recent years, with particularly high-profile activity by republicans in the past year. They say intimidating and attacking suspected drug dealers is part of a campaign to increase support for the IRA's political wing, Sinn Fein.
A similar campaign of beatings and intimidation took place in Kerry from late 1997 to early last year. Local Garda sources said the Kerry anti-drugs activity was co-ordinated by the local IRA leader.
The IRA carried out a much more violent campaign against alleged drug dealers in Northern Ireland. Between the calling of the first IRA ceasefire in August 1994 and 1998, the IRA killed nine men suspected of involvement in drugs in Belfast.
The last killing was of Mr Brendan Campbell in Belfast in February last year. That killing, a day after another IRA murder of a leading south Belfast loyalist, Mr Robert Dougan, led to Sinn Fein's temporary expulsion from the talks that led to the Belfast Agreement.
Yesterday's shooting follows the revelation, during the trial of the men who killed Det Garda Jerry McCabe, that the IRA had intimidated a witness. The State reduced the charge of murder against four IRA members to manslaughter after a main witness in the case, Mr Patrick Harty, a farmer, refused to give evidence.
Mr Harty had made statements to detectives implicating members of the Munster IRA in Det Garda McCabe's killing. However, when he was brought to the Special Criminal Court he said he would not testify and was jailed for contempt. His solicitor told the court that Mr Harty was "in fear of his life". He was released from prison just over a week later.