Hisham Talaat Moustafa was a high-profile member of the ruling party
Egypt's highest court has ordered the retrial of a tycoon and an ex-policeman who were sentenced to death for killing a popular Lebanese singer.
The tycoon, Hisham Talaat Moustafa, was found guilty last year of paying Muhsin Sukkari $2m (£1.3m) to kill Suzanne Tamim in Dubai in July 2008.
The court overturned their murder convictions on procedural grounds.
The case has received much attention, as it involves a member of an elite often seen as being above the law.
Thursday's ruling prompted cheers and clapping from the billionaire tycoon's relatives in the Cairo courtroom.
Mr Moustafa, 50, was a hugely powerful business tycoon, a high-profile member of the ruling party and a friend of the son of Egyptian President Hosni Mubarak.
Christian Fraser, BBC News, Cairo
The Court of Cassation has not yet detailed the reasons behind its decision. The case will now return to a criminal court later in the year. In the meantime questions will undoubtedly be asked whether Mr Moustafa has escaped the gallows because of his position in society.
He is close to the president's son, Gamal Mubarak, and a former member of the ruling National Democratic Party's policy-making committee.
When Egypt denied Dubai's extradition request during the investigation, the Dubai police sought assurances from Egypt that it would pursue the case; and given the huge media attention the Egyptians had little option but to comply. There will certainly be suspicions in some quarters that pressure has been put on the courts or the judges.
In the past, corporate cases of manslaughter or corruption have been cut short because those facing the charges were associated with the ruling class.
He had a relationship with Ms Tamim, who had found fame as the winner of an Arabic television talent show.
Prosecutors at the murder trial last May said that when Ms Tamim spurned Mr Moustafa's offer of marriage, he plotted to kill her.
Mr Sukkari, a security guard at a hotel owned by Mr Moustafa, was said to have travelled to Dubai, where he stabbed Ms Tamim to death at her flat.
Defence lawyers had handed a 422-page document to judges outlining 41 arguments for a retrial.
During the original trial the prosecution played tapes of phone calls between the two suspects.
In the transcript the two talk about where and how to commit the murder. But defence lawyers have said they are fake.
They also argue that at a crucial early stage of the case, Mr Sukkari did not have a lawyer.
Appeal lawyers also claimed the Dubai police investigation into the murder was flawed.
Dubai police gave the Egyptian authorities DNA evidence linking Mr Sukkari to the scene of the murder.
They said he was also caught on CCTV leaving Ms Tamim's apartment block.
A Dubai shoe shop also identified Mr Sukkari as the man who bought a shoe which left a bloodstained print in the flat where Ms Tamim's body - her throat slit - was discovered.
In Mr Sukkari's Egyptian apartment, police found the money they said Mr Moustafa had given him.