Tamim's killing has gripped much of the Middle East
Egyptian tycoon and legislator Hisham Talaat Moustafa and a security guard have pleaded not guilty to the murder of Lebanese pop star Suzanne Tamim.
Mr Moustafa is accused of paying security guard Muhsin Sukkari to kill Tamim in Dubai in July.
Tamim had reportedly broken off a relationship with Mr Moustafa several months before she was stabbed to death.
The trial, involving wealth, politics and showbusiness, has gripped the attention of Egypt and the Middle East.
The prosecutors allege that Mr Moustafa paid Mr Sukkari $2m (£1.2m) to kill Ms Tamim in revenge for breaking up with him.
Mr Sukkari is a former Egyptian police officer who was a security guard at a hotel owned by Mr Moustafa.
The prosecution presented evidence including alleged recordings of phone calls between the billionaire and the security guard, video from a security camera said to show Mr Sukkari at the singer's Dubai apartment, and traces of Mr Sukkari's DNA on clothing allegedly left near the murder scene.
They say Mr Sukkari went to Ms Tamim's apartment posing as a worker for the building's owner in order to gain admittance. She was stabbed repeatedly and her throat was cut.
Suzanne Tamim rose to fame after appearing on a Lebanese talent show
The Egyptian prosecutor said Mr Sukkari - who was arrested in August - had reported Mr Moustafa's involvement in the case.
"I didn't kill Suzanne. I didn't do it," said Mr Sukkari in court.
Mr Moustafa also said he was innocent. "It didn't happen. I presented all evidence to prove that it didn't. I ask for God's protection for he is my best advocate."
The pair could face the death penalty if convicted.
The case has been adjourned until 15 November and the two defendants have been remanded in custody.
There was heavy security around the Cairo courthouse for the start of the trial.
Egyptian prosecutors had originally banned media reports, and many thought the case - involving such a prominent figure as Mr Moustafa - would never come to court, says the BBC's Yolande Knell in Cairo.
Tamim rose to fame after appearing on a TV talent show in Lebanon in 1996, but her career was marred by stories about a troubled private life.
Mr Moustafa is a billionaire property developer and a leading figure in the ruling National Democratic Party who sat on the Shura Council, Egypt's upper legislative house.
He has been stripped of his parliamentary immunity.
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