Two Middlesbrough men convicted of killing market trader Kalvant Singh almost four years ago have launched an appeal to have their murder convictions quashed.

Thomas Petch, 26, of no fixed abode, and George Romero Coleman, 45, of Thornton Street, North Ormesby, were found guilty and jailed for life at Teesside Crown Court in March 2002.

The pair were said to have engaged in an orgy of violence sparked by a turf war, leading to Mr Singh being hurled to his death from a window in Errol Street, Middlesbrough.

But both claim their convictions are unfair as the man who committed the fatal act, Jonathan Crossling, later had a guilty plea accepted for manslaughter. After being extradited from his hideaway in Spain, Crossling, of Hillside Avenue, Grove Hill, Middlesbrough, was jailed for 18 years in June 2003, having admitted manslaughter, four counts of grievous bodily harm with intent, and one of aggravated burglary. That was later cut to 14 years.

Tom Bayliss QC, for Petch, told London's Criminal Appeal Court that he was only a secondary participant in the killing and the trial judge should have ruled he had no case to answer on the murder charge. Similar grounds of appeal were put foward for Coleman. The pair must now wait for the decision.