Metropolitan Police officers worked with the British Transport Police and neighbouring forces to arrest and convict John Duffy and David Mulcahy, for 18 rapes of women and young girls at or near railway stations in London and South East England and murdering three of their victims between 1982 and 1986. In 1986 Met officers also secured the conviction of Kenneth Erskine for a series of attacks in Stockwell on elderly men and women, breaking into their homes and strangling them to death. In March 1987 private investigator Daniel Morgan was murdered in Sydenham (south east London), in March 1987. He was said to have been close to exposing police corruption, or involved with Maltese drug dealers. Morgan's death has been the subject of several failed police inquiries, and in 2011 it was at the centre of allegations concerning the suspect conduct of journalists with the British tabloid News of the World. This unsolved murder has been described as a reminder of the culture of corruption and unaccountability within the Metropolitan Police Service. Metropolitan Police officers assisted the British Transport Police during the 1987 King's Cross fire and the 1988 Clapham Junction rail crash.