Police release four men quizzed over estate agent kililng

Four men were released on bail last night after being questioned by detectives about the murder of Tim Robinson, the estate agent who was stabbed to death in front of his girlfriend.

Three men, aged 17, 18 and 20, were arrested by the Metropolitan Police yesterday morning. A fourth man, aged 19, was arrested later after voluntarily going to a police station. The four have all been released on bail to return to south London police stations in early March.

Mr Robinson, 25, was stabbed through the heart in front of his girlfriend, Jemma Joyce, 26, outside their home in Battersea, south-west London, on 27 January. He had apparently stopped to help two men who had asked for directions.

There has been speculation that he died in an attempted "carjacking" but detectives said there was no evidence that his Audi was being targeted. After the attack the killers fled on foot leaving the vehicle behind.

The police are investigating several leads, including reports that Mr Robinson was among several people who had complained about noise caused by a pirate radio station operating close to his home.

Residents had repeatedly protested about aggressive youths and loud noise. The illegal radio station is believed to have closed down shortly after the attack and the police want to question the organisers of the station.

A Scotland Yard spokesman said: "Officers investigating the murder are aware of the existence of a pirate radio station, which is near the scene of the crime. However there's no evidence to connect this to the murder. It's just one of a number of lines of inquiry."

Mr Robinson had picked up Ms Joyce, a trainee teacher, from London's West End before the attack at 10pm. As she directed him into a tight parking space outside their home two men asked her for directions. Mr Robinson finished parking the car and got out to ask the men where they wanted to go and within moments he had been stabbed half a dozen times in the face, chest and upper arm. He was taken to St Thomas's Hospital, where he died three days later.

Detectives are still appealing for a white boy – aged about 13 or 14 – who a witness mentioned as having been nearby at the time of the incident, to come forward. He was on a mountain bike and may have been wearing a red jacket.