The gun used to murder the BBC presenter Jill Dando at her Fulham home on Monday was "the weapon of choice" of the professional criminal, a leading criminologist has said.
A post mortem on Monday night found Ms Dando, a former presenter of the BBC's Crimewatch programme, died from a single gunshot wound to the side of her head. And police yesterday confirmed she had been shot at very close range by a gunman using a 9 mm semi-automatic weapon.
Fuelling speculation that Ms Dando may have been the victim of a professional or "contract" killing, Ms Kate Broadhurst, of the Scarman Centre for the Study of Public Order in Leicester, said: "The sawn-off shotgun is the weapon of choice for the bank robber . . . this is the weapon of the drug dealer and the weapon of the professional criminal."
As police continued a massive search for the murder weapon - and for the prime suspect, first seen in Gowan Avenue an hour before the killing - Ms Broadhurst suggested the weapon could have been hired from a professional armoury for a day or a week.
There was no confirmation from Scotland Yard that the shooting had been carried out by a professional "hit man", the officer leading the murder inquiry, Det Chief Insp Hamish Campbell, saying only that his team were examining all possible motives.
Insp Campbell issued a fresh appeal for witnesses who might have seen the suspect, who probably staked out Ms Dando's home for an hour before the killing, as detectives detailed several sightings of the smartly dressed white man with the mobile phone, who may have donned heavy black-framed spectacles in an attempted disguise.
Insp Campbell said police had yet to trace anyone who heard the fatal gunshot. The shot might have been muffled for any number of reasons, he told Sky News, and it was possible a silencer was used.
As police scoured gardens in Gowan Avenue and a neighbouring building site, Mr Campbell was particularly anxious to hear from anyone who might have seen the suspect prior to the shooting. "He was seen up to an hour before the shooting. What was he doing before then? Was he visiting a shop, was he buying cigarettes? Where did he go after the shooting? Did he return home in an agitated state? Was he missing from work for a short period?"
He also appealed for information from anyone who might have been involved in the supply of the murder weapon through the illegal network.
Mr Campbell said Ms Dando had not recently expressed any concerns about being stalked. And Ms Broadhurst suggested that while a professional hit man could easily have acquired the murder weapon, it would have been more difficult for a jilted lover or stalker. "He would have to make a conscious effort. He couldn't walk into a pub in the East End and get one. Your face would have to fit in those kinds of circumstances," she said.