Diaz (centre) was starring in Charlie's Angels: Full Throttle at the time

On his second day of testimony, John Rutter told the jury he thought the signature on a release form was real.

But he said he accepted the signature was probably not real.

Mr Rutter denies forging Ms Diaz's signature and attempted grand theft in a bid to extort money from the actress. He also faces a perjury charge.

'Right of refusal'

Mr Rutter had tried to sell the pictures - taken 11 years ago when she was a model - for $3.5m (�2m) shortly before the opening of Diaz's recent film Charlie's Angels: Full Throttle.

Mr Rutter testified he was going to give the Hollywood star "right of first refusal" before trying to sell the photographs elsewhere.

If convicted, Mr Rutter could face up to six years in prison. An extortion charge he was facing was dropped before the case went to trial.

His perjury charge comes from a statement in which the photographer said he had kept an original copy of Ms Diaz's model release form since the shoot.

After cross-examination, he acknowledged he had not actually seen the form until an aide showed it to him on a computer in 2002.

Ms Diaz, 32, said last week she had never signed a release form for the shoot.

A judge has ordered a permanent injunction prohibiting Mr Rutter from distributing the picture.