The man accused of murdering Norfolk security guard Paul Cavanagh has claimed that key witnesses lied about seeing him plunge a knife into his victim's neck.

The drug dealer accused of murdering Norfolk security guard Paul Cavanagh has claimed that key witnesses lied about seeing him plunge a knife into his victim's neck.

David Watson, 20, from Hackney in east London, maintains he stabbed 30-year-old Mr Cavanagh by accident as he struggled to escape before police arrived.

He had been detained at the HMV store in Chapelfield Shopping Centre, Norwich, for stealing a CD but claims he panicked when officers were called as he was carrying £1,400 of crack cocaine and heroin. He says he was being threatened by a supplier who he owed tens of thousands of pounds.

A number of witnesses, including second security guard Gavin Levett who was also stabbed as Watson fled, claim he deliberately used the knife. Mr Levett said he saw the knife moving towards Mr Cavanagh's neck. Customers in the store had earlier told Norwich Crown Court that they saw Watson plunging the knife into Mr Levett's shoulder.

However, Watson insists that he was only using the knife to scare the men off and stabbed them by accident when they tried to stop him. He said: “Mr Cavanagh died because we were in a struggle. It was not his fault; it was because of my reckless behaviour. But I did not want this to happen.”

The jury was told that although Watson denies murder he has already admitted manslaughter. He denies wounding Mr Levett with intent to cause serious harm but admits wounding him. He denies a third charge of attempted wounding with intent which relates to claims he tried to stab off duty special constable Ian Gardiner who was pursuing him.

Earlier in the week two prison officers told the court Watson had admitted stabbing Mr Cavanagh, of Rockland St Mary, near Norwich. Yesterday Watson told the court these accounts were not true and also said other witnesses who saw him deliberately use the knife were mistaken or were not telling the truth.

Security camera footage of the events leading up to the stabbing was shown to the court again and at one point Mr Cavanagh was shown on his knees with his hands in the air in a position which suggested he was surrendering.

The prosecution claims this was the point at which he suffered “defence wounds” suggesting Watson had already attempted to stab him once before striking the fatal blow.

The case continues and the jury is expected to be sent out to consider its verdict on Tuesday.