The trial of four senior Egyptian security officials accused of the kidnap, torture and murder of Italian student Giulio Regeni in 2016 gets underway in Rome on Tuesday.

The opening hearing marks the second time the four security officers will go on trial in absentia. The first trial was halted in 2021 after it was argued there was no certainty the men had been officially notified that they were charged with Regeni's death.

The four defendants have been identified as senior officers in Egypt's domestic security agency.

What do we know about Regeni's death?

Regeni, who was 28 at the time of his death, had been conducting research in Cairo for his doctoral thesis, when he was abducted in January 2016. His body was discovered nine days later, dumped near a highway and showing signs of torture.

His mother said his body was so mutilated that she was only able to recognize the "tip of his nose" when she viewed it.

The family's lawyer said that five of his teeth were broken, and 15 of his bones had been fractured, while letters were found carved into his skin.

Human rights activists have said the injuries on Regeni's body resembled those resulting from torture in Egyptian Security Agency facilities.

Strained ties after student's death

Regeni's death strained relations between Italy and Egypt, with Italian lawmakers accusing Cairo of being hostile to attempts at securing justice.

At one point, Italy withdrew its ambassador in an effort to press Egypt into cooperating with the investigation.

Investigators believe Regeni was abducted and killed after being mistaken for a foreign spy.

Egyptian authorities claim the Cambridge University doctoral student was the victim of common robbers.

kb/nm (AP, AFP)