Cairo prosecution ordered Friday the detention for four days pending investigations of three family members related to an alleged gang member linked to the murder of Italian student Giulio Regeni, state news agency MENA reported.

Thursday, Egyptian police said they found the passport and other identity documents of the murdered Italian student inside an apartment linked to a gang “specialised in robbing foreigners.”

Four gang members were killed hours before the announcement in an exchange of fire with police, the interior ministry said.

Regeni’s belongings were found in the apartment of a sister of one the gang members. The sister, wife, and brother-in-law of the alleged gang member are the ones arrested.

All three are being investigated for “covering up for a criminal and hiding him from justice, and keeping stolen items, knowing they were the product of criminal activity.”

Regeni's body was found with signs of torture on a roadside on the outskirts of Cairo nine days after he disappeared on 25 January. 

The 28-year-old doctoral student was conducting research on independent trade union movements in Egypt. 

Italian Investigators pointed to “inconsistencies” in the latest information in the case provided by Egypt, according to Italian news agency ANSA, to the effect that it would be unlikely that Regeni's kidnappers would hold on to “compromising evidence” weeks after his death.

They also said the kidnappers were unlikely to torture the victim over the course of a week if their aim was to obtain a ransom.