Egypt's Supreme State Security Prosecution prosecution ordered the detention of six suspects for 15 days pending investigation into charges of killing the prosecutor-general in June 2015, the prosecutor’s office said in a statement on Sunday.
The defendants, who were arrested on Saturday, are the first to be identified as suspects in the murder.
Prosecutor-general Hisham Barakat died from injuries sustained in a Cairo bomb attack; the first successful assassination attempt against a state official since an upswing in militant violence following the 2013 ouster of Islamist president Mohamed Morsi.
Two drivers and five members of security forces were also injured when the blast hit the prosecutor's convoy near the military academy in the upscale Cairo district of Heliopolis.
No group has claimed responsibility for the attack so far, but there have been unconfirmed reports that the Islamic State militant group was behind the killing.