On 10 March 1987 after having a drink with Jonathan Rees, his partner in Southern Investigations, at the Golden Lion pub in Sydenham, Morgan was found dead in the pub car park next to his car, with an axe wound to the back of his head. Although a watch had been stolen his wallet had been left and a large sum of money was still in his jacket pocket. The pocket of his trousers had been torn open and notes he had earlier been seen writing were missing. Subsequently a match to the DNA sample found on Morgan’s trouser pocket was allegedly made. Morgan was alleged to have been investigating drug-related police corruption in south London before his death.
Detective Sergeant Sid Fillery, stationed at Catford police station, was assigned to the case but did not reveal to superiors that he had been working unofficially for Southern Investigations. In April 1987 six individuals including Sid Fillery and Jonathan Rees, the brothers Glenn and Garry Vian and two Metropolitan police officers were arrested on suspicion of murder but all were eventually released without charge.
At the inquest into Morgan’s death in April 1988 it was alleged that Jonathan Rees, who had had disagreements with Morgan, told Kevin Lennon, an accountant at Southern Investigations, that police officers at Catford police station who were friends of his were either going to murder Danny Morgan or would arrange it, and Sid Fillery would replace Morgan as Rees’s partner. When asked, Rees denied murdering Daniel Morgan. Sid Fillery, who had retired from the Metropolitan Police on medical grounds and joined Southern Investigations as Rees’s business partner, was alleged by witnesses to have tampered with evidence and attempted to interfere with witnesses during the inquiry.