Egypt and Rome prosecutors said Wednesday surveillance footage from the Cairo subway system on the day a slain Italian researcher disappeared does not include images of him. However, there are gaps in the footage, they said.

The recordings do not show Giulio Regeni inside or near any metro stations, a joint statement by both prosecutors said. The gaps in the recordings, however, need “further sophisticated examinations,” they said.

Regeni, 28, was a Cambridge University doctoral student researching labor movements in Egypt when he disappeared in Cairo in Jan. 25, 2016. His body was found on a roadside several days later bearing marks of extensive, dayslong torture of the kind that activists and rights groups say is widespread within Egyptian detention facilities.

Egypt’s security services have denied any involvement in Regeni’s abduction or death.

Since Regeni’s body was found, the Egyptian government has suggested several alternative scenarios for his death.

It claimed that security forces killed members of a kidnapping gang in a raid and circulated photos of Regeni’s ID cards it said were found at the scene of the raid. That explanation was widely dismissed, including in the Italian media, which has closely followed the case.

Earlier this year, Egypt’s President Abdel-Fattah el-Sissi accused unknown parties of being responsible for murdering Regeni, alleging a failed plot to sabotage Egyptian-Italian relations.

Regeni had been researching labor movements in Egypt, a sensitive subject that would have drawn scrutiny from security agencies. He went missing in central Cairo when police were out in force to prevent protests on the fifth anniversary of the 2011 uprising that toppled autocrat Hosni Mubarak. His main contact in the unofficial street vendors’ union later said he had told police that Regeni was a spy.

Egypt has been waging a fierce crackdown on dissent since the military overthrow of an elected but divisive Islamist president in 2013. Thousands of people have been jailed, mainly Islamists but also several prominent secular activists. Pro-government media routinely portray Egypt as the target of foreign conspiracies aimed at destabilizing the country.