Experts remain perplexed as to the motives behind the death of Cambridge PhD student Giulio Regeni, as the Egyptian investigation refuses to look into accusations of security service complicity.

While many in the Egyptian and Italian media have insinuated foul play on behalf of the Egyptian security services, the Egyptian government has emphatically rejected these claims, suggesting criminal motives may have been at play.

For experts who study human rights in Egypt, Regeni’s injuries bear the hallmarks of an extrajudicial killing at the hands of the security services.

But this case is puzzling because it is the first time the victim was a foreign academic. Usually, one could expect the state to harass or deport such an individual, but the foreign passport should have protected him physically.

Rumours have surfaced in the Italian media suggesting that Regeni may have been gathering information for the Italian intelligence agency, with journalists citing the historical ties between universities and intelligence, as well as Regeni’s brief time at British-American security consultancy Oxford Analytica.

But while this might explain extraordinary action by the Egyptian state, the Regeni family have called such suggestions offensive to his memory.

An explanation suggested by Marina Calculli, a Fulbright scholar at the George Washington University who has worked in the region, is that it was simply an irredeemable mistake.

“The case of Giulio is strange because he was [apparently] in detention for days,” Calculli said. “It could be that somehow he was taken and detained and tortured in this kind of anti-foreigner, anti-researcher hysteria and perhaps they crossed a line and could not come back.

“You cannot just release a foreigner that has been tortured, because you are exposing to the world what you are doing inside your prisons.”

Speaking to Italian newspaper Corriere della Sera, the Foreign Minister Sameh Shoukry dismissed the idea, calling the suggestions of complicity merely “judgments, accusations and insinuations, unjustified and without proof.”

Instead, the investigation is largely being focused on Regeni’s close friends and contacts, with the security forces mainly questioning these people, in at least one case without a lawyer.

The Interior Ministry has said that their investigation pointed towards several possibilities, including murder as an act of revenge, or other criminal motives, noting: “the Italian had many relationships with people near where he lives and where he studied”.

Though the nature and violence of Regeni’s injuries seem to make personal disagreement an unlikely cause, there is little chance of the security services, who are themselves tasked with drawing up a list of suspects, investigating one of their own.