An uncle of Neil McConville - shot dead outside Lisburn in April 2003 - said the family was "disappointed" in the Police Ombudsman's report on the killing issued yesterday.

Ombudsman Nuala O'Loan yesterday cleared the police officer who shot the 21-year-old.

But she expressed "grave concern" about other aspects of the case - saying the operation that led to the killing was "poorly managed by senior officers" and employed a "high-risk strategy".

McConville's family is now preparing to take legal action against police.

Mrs O'Loan's report also said that one of the PSNI's most senior officers tried to block her investigators from getting access to intelligence material about the shooting.

And when they were allowed to see it - more than six weeks after the shooting - a piece of intelligence which was "critical to the investigation" had been wiped from a police computer.

She also revealed that several senior officers who may have been subject to discipline retired before her investigation could be completed.

McConville, from Bleary, Co Down, was shot three times behind the wheel of a Vauxhall Cavalier when police feared he would drive off over another officer who had been knocked over by the car.

Police stopped the car because they suspected his passenger, David Somers - who had been involved in the plot to murder David Barnes in north Belfast weeks earlier - was preparing to shoot a man.

An unloaded sawn-off shotgun was found in the car.

Mrs O'Loan said she had "no criticism" of the policeman who fired the fatal shots, but she criticised several other officers, including an Assistant Chief Constable she accused of trying to stop her investigators from getting access to intelligence about the police operation.

Barney McConville, Neil's uncle, said the release of the report yesterday was "very difficult" for the family.

"A lot of it we knew about already," he said. "But our main problem is the way PSNI officers played the Ombudsman.

"The Ombudsman has failed to deliver an adequate report because the PSNI haven't co-operated fully with her.

"They turned the investigation into a farce. It took two- and-a-half years to interview one officer. That's totally unacceptable.

"This whole issue of retirement before investigation just stinks. It's hard for us to accept that people may have set out to frustrate this investigation and they can still retire with their pensions.

"It's a tactic that's happened before and something should be done about it."

Yesterday, the PSNI said it regretted McConville's killing and defended the policies in place to deal with retirement in the face of discipline.

"All officers applying for severance are subject to discipline vetting by PSNI Professional Standards and the Police Ombudsman," a PSNI statement said.

"Each application is examined thoroughly and each case is decided on its own distinct circumstances. Considerations include the seriousness of the offence under investigation as well as medical and personal issues.

"These processes were recently examined by the Policing Board's Human Rights advisers who are satisfied with their effectiveness."

Mark Thompson, director of the pressure group Relatives for Justice, said a review of the Ombudsman's powers must address the "loophole" that puts retired officers beyond her remit.