Former detective among six arrested over 1987 murder

The unsolved murder of a private investigator 21 years ago which prompted claims that it was linked to police corruption moved closer to resolution yesterday after it was announced six people including a former detective had been arrested in connection with the killing.

Daniel Morgan, 37, was found in a pub car park in Sydenham, south-east London, with an axe embedded in his head on 10 March 1987 after he had been drinking with his business partner. His family have campaigned tirelessly to prove that he was on the verge of exposing a drug dealing network with possible links to corrupt police officers.

The case – and the failure to bring charges against any suspects, despite four investigations by the Metropolitan Police – has proved a longstanding embarrassment to the Yard after it was held up as evidence of a failure to root out alleged wrongdoing within Britain's largest force.

But a new inquiry led by Assistant Commissioner John Yates, the officer who led the cash-for-honours investigation that tarnished Tony Blair's last months in office, reported new developments yesterday with the arrest of five men on suspicion of carrying out the murder. A sixth man, a 24-year-old serving police constable, was held for misconduct in a public office, understood to relate to the alleged leaking of information about the current inquiry.

Sources said that the arrests were part on an ongoing operation, involving up to 20 detectives, which is still following multiple lines of inquiry. Senior officers, who have already persuaded two "supergrasses" to enter a witness protection programme in relation to the case, called for a number of outstanding witnesses to come forward.

Mr Yates said: "The current investigation has shown that there are still people out there who have highly pertinent evidence about this case. The arrests demonstrate the Met's continued determination to bring those responsible to justice. I also hope that these arrests are a reassurance to those in the community who also have the information or evidence about what happened to Daniel. We have long said that within south London, the identity of those responsible for the murder is one of the worst-kept secrets."

Three of the suspects were originally arrested in 2006 and another two men were detained at a London police station yesterday. It is understood one of those arrested is Jonathan Rees, Mr Morgan's partner in Southern Investigations, the private eye agency they set up in 1984. Another is a former Yard detective who was part of the original murder investigation.

Mr Morgan, a rugby-loving father of two, was struck many times about the head as he sat in his BMW outside the Golden Lion pub on Sydenham High Street. His £900 Rolex watch was missing but a wallet containing £1,100 was still in the pocket of his suit. The handle of the axe used in the attack had been wrapped in fabric plasters to prevent any fingerprints being left.

Mr Rees, who left the pub 15 minutes before the murder, was arrested in connection with the killing but never faced trial.

But despite an admission that the initial murder inquiry was compromised, little new evidence was uncovered. The latest technology is thought to have been used to examine DNA evidence left on Mr Morgan's suit and traces on the axe handle.