Naked from the waist down, the mutilated body was found on the outskirts of Cairo, lying in a ditch beside the road that runs through the desert to Alexandria. Giulio Regeni, a 28-year-old Italian student in Egypt, had met a slow and agonising end.

His body showed signs of torture, including stab wounds, bruising, a severed ear and cigarette burns. The student, from Fiumicello in the north-east of Italy, suffered “a slow death”, said the Cairo prosecutor Ahmed Nagi.

Rome is demanding that its experts be allowed investigate the death of Mr Regeni, amid conflicting reports from Egyptian officials about the circumstances of his death and concerns about human rights abuses in the violence-torn nation.

Mr Regeni was found in the ditch on Wednesday. He had been studying for an economics PhD when he went missing on 25 January, in what Italy’s foreign ministry has called “mysterious circumstances”.

Giulio Regeni

One of Mr Regeni’s Egyptian friends said that at the time of his death, he had been seeking contacts for trade union activists to interview as part of his PhD research. His body was discovered after an online campaign to find him was launched.

Suspicions of a cover-up by security forces increased after local media quoted a police official, General Khaled Shalabi, as having excluded foul play. He was reported as saying: “The first investigations suggest he was the victim of a car accident” – despite the prosecutor’s description of apparent torture and the fact that Mr Regeni was found naked from the waist down.

The police account was also contradicted by the Egyptian ambassador to Rome, who promised “full co-operation to identify those responsible for this criminal act”.

The Italian foreign ministry’s director general, Michele Valensise, “urgently” summoned the Egyptian ambassador Amr Mostafa Kamal Helmy. And Italy’s Foreign Minister Paolo Gentiloni demanded that Italy be allowed to participate in the investigation. “We firmly call on Egypt to allow the Italian authorities to collaborate in the investigation in Cairo into the death of our citizen, because we want the truth to come out,” he said. “We owe it to the family.”

Reports suggested that a team of Italian investigators was ready to fly to Cairo. The Italian Economic Development Minister Federica Guidi cut short her trade mission to Egypt, and is thought to have urged the Egyptian President Abdel Fattah al-Sisi to intervene in the case.

The leading Egyptian human rights lawyer Mohamed Sobhy wrote on Facebook that “a remarkable number of national security personnel” had gathered at the Zeinhom morgue in Cairo and that he had not been allowed to see Mr Regeni’s body.

Observers say that Egyptian authorities intensified their crackdown on dissent in the run-up to 25 January – the fifth anniversary of the uprising that toppled Hosni Mubarak – fearing large-scale protests.

A friend of Mr Regeni told Al-Ahram newspaper that he had received several requests from the student for names of “workers’ rights activists”, but that Mr Regeni had promised he would not to seek to meet them on 25 January, given that political tensions would be running high. The friend also claimed Mr Regeni’s political research had been the main focus when he was questioned by the police following the Italian’s disappearance.

Three days after he had gone missing, the Ahram news website reported that police had arrested dozens of Egyptians and foreign nationals as part of a security campaign in Giza against “fugitives and violators”.

Human rights groups say Egyptians are often detained by police on little evidence and beaten or coerced. Many have disappeared since 2013. Egypt denies allegations of police brutality. Gianni Rufini, the head of Amnesty International’s Italian division, expressed its solidarity with Mr Regeni’s family and demanded a “rapid, thorough and independent investigation,” adding “torture was the norm” in Egypt.

Other local media sources suggested that Mr Regeni may have been the victim of a violent robbery, or a kidnapping gone wrong, or the target of jihadists intent on damaging Egypt’s efforts to attract tourism and foreign investment. One police source suggested that the killing might have been linked to unspecified events in Mr Regeni’s personal life.

On the evening he disappeared, Mr Regeni reportedly left his flat in the smart el-Dokki area of Giza, part of Greater Cairo, at around 8pm to meet friends at a birthday party in the centre of Cairo. He never arrived. His body was found many miles from both locations, nine days later.

A post-mortem examination report will be sent to prosecutors, sources told Ansa news agency. Orders have been given to question Mr Regeni’s friends as part of the investigation, the prosecution sources added. Mr Regeni spoke good Arabic, and had been in Cairo since October. His research focused on trade unions in Egypt after the 2011 uprising.

His parents arrived in Cairo on Thursday and his mother released a very brief statement saying: “My grief is felt by the whole of Fiumicello.”