According to Gholamhossein Rahbarpour, chief judge at the Tehran Revolutionary Court, two of the sentences have already been approved by the Supreme Court, while two were under judicial review. "Other dossiers with heavy punishments are also under investigation," he told the conservative newspaper Jomhuri Eslami yesterday, in a clear hint that others among the 1,000 people still in detention could face the death penalty.
The riots, in which five people were killed and dozens more injured, were in response to a vigilante crackdown on student protests at the closing of a pro-reform newspaper, and quickly developed into the worst unrest in Iran since the 1979 revolution which overthrew the Shah.
Mr Khatami survived the turmoil - but at a considerable political price. Not only did the riots give hardliners a chance to arrest many of his leading pro-democracy student supporters; they also forced the President to drop efforts to strip a key conservative religious council of its power to veto candidates for February's parliamentary elections.
More than ever, that vote is developing into a showdown between the conservative and reformist blocs in the establishment. President Khatami's election in May 1997 was a major victory for the latter, and was followed by a relaxation of some especially strict tenets of Islamic rule, overtures to traditional foes including Saudi Arabia and the United States, and a part-lifting of the fatwa against the British author Salman Rushdie.
But lately the pendulum has been swinging in the opposite direction, back towards conservatives grouped around the country's supreme leader, Ayatollah Ali Khamenei. Pro- reform newspapers have been closed, intellectuals jailed and hardline clerics appointed to important positions.
In recent days, a senior religious figure has branded some of the July protesters as mohareb, "those who declare war on God", while Mr Rahbarpour yesterday accused the students of ignoring the wider interests of the theocratic Islamic state. The four who had been sentenced to death, he said, had links with "certain political groupings", which he declined to specify.
The judge also told the newspaper that there was evidence to prove the guilt of 13 Iranian Jews arrested earlier this year on charges of spying for Israel. The case is being handled by a court in the southern city of Shiraz. If convicted, they could be executed under a 1996 law stipulating the death penalty for anyone guilty of spying for either Israel or the US.