Lana Clarkson was found shot in the face

Captain Frank Merriman, of the Los Angeles County Sheriff's Department, said it was believed that Lana Clarkson's shooting at Mr Spector's mansion was a criminal act.

Speaking for the first time about the case, Mr Spector's lawyer Robert Shapiro said he believed his client was innocent.

Mr Spector was arrested on suspicion of first degree murder on 3 February after Ms Clarkson, 40, was found dead at his hilltop home in the city's Alhambra district.

Mr Shapiro said: "I am convinced that the thorough and accurate investigation of the evidence by the Los Angeles sheriff's department, its criminalists and the county coroner will prove that Phil Spector is innocent of any crime."

Ms Clarkson had gone home with Mr Spector after a night at the House of Blues club in West Hollywood, where she worked as a hostess.

No charges have been filed against him, and he has been released on $1m bail.

Captain Merriman said the investigation could continue until the summer because of complex evidence and the length of forensic tests.

He disputed news reports that said the 62-year-old producer would soon be cleared.

Mr Spector is a legendary name in pop music for his work with acts such as John Lennon, Tina Turner, Ramones and Leonard Cohen.

He is known for the so-called Wall of Sound production technique, a process he perfected during the 1960s with artists such as the Ronettes and Shirelles.