Dr Pena indicated the path of the bullet that killed Clarkson

Dr Louis Pena said bruising suggested the barrel of a gun may have been forced into Ms Clarkson's mouth before she was fatally shot in 2003.

Ms Clarkson was a hopeful person with no history of depression or suicide attempts, he told the court.

Mr Spector, 67, is accused of killing Ms Clarkson at his Hollywood mansion. The defence says she shot herself.

It says she placed the gun in her mouth and pulled the trigger.

'Blunt-force trauma'

Dr Pena also told the court that there were bruises on Ms Clarkson's right arm and wrist but could not confirm the cause of the marks.

Referring to the bruise on her tongue, he said it was "very unique and is consistent with blunt-force trauma. Something struck the tongue".

Dr Pena said there was no evidence that Ms Clarkson had been preparing to kill herself and that she died with a purse on one shoulder, which, he said, was not typical of a suicide.

"I found her to be a hopeful person from the notes I read," he said.

Ms Clarkson had been taking two drugs generally given for depression at the time of her death, but her neurologist had prescribed them for her chronic headaches, Dr Pena said.

Lawyers for Mr Spector say Clarkson killed herself

Dr Pena conceded he was not an expert in gunshot residue or blood spatter and acknowledged he consulted textbooks in coming to his conclusions.

Mr Spector pioneered the "Wall of Sound" recording technique in the 60s, working with stars such as The Beatles, Tina Turner and The Righteous Brothers.

He is accused of killing is Ms Clarkson, 40, on 3 February 2003, hours after meeting her at the Sunset Strip nightclub House of Blues where she worked.

If convicted, Mr Spector faces between 15 years and life in prison.