Rival loyalist terrorist groups may have joined forces to murder a Catholic teenager in Antrim almost six years ago
A detective told the inquest the killing of 19-year-old Ciaran Cummings was "absolutely brutal".
Mr Cummings was shot with a sawn-off shotgun as he waited for a lift at Greystone Road roundabout in July 2001.
The inquest was told that there were four separate claims of responsibility after the shooting.
Two came from the Red Hand Defenders, a cover name sometimes used by the UFF, another by the Orange Volunteers, while a fourth from the Loyalist Volunteer Force denied any involvement, but blamed the rival UVF.
Detective Chief Inspector Frankie Taylor told Belfast Coroner's Court: "It indicates to me that there was perhaps one, maybe two organisations involved.
"Perhaps one organisation carried it out with the logistical support of another.
"It would be my assessment that the Red Hand Defenders were involved. They would have had support from the mainstream UVF."
Mr Cummings tried to flee after being hit by the first blast from the shotgun fired by a man on the back of a motorcycle.
The pillion passenger then get off the bike and chased him.
After he stumbled and fell the gunman pinned him down with his feet and fired again from point-blank range.
Despite nine arrests, no-one has been convicted of the welder's murder and DCI Taylor said a new review of all evidence is to be carried out.
The murdered teenager's father, Robert Cummings, told how he rushed to the scene, thinking his son had been knocked down.
Mr Cummings said: "I checked Ciaran's pulse, but there was nothing.
"Then I took a mobile phone out of Ciaran's pocket as it was ringing. It was his girlfriend Catherine."
Coroner John Lecky said the murder was sectarian and he hoped the police's efforts to bring the killers to justice would be successful.
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