The bombing of a Coptic Church in the Egyptian city of Alexandria last New Year's Eve left 21 people dead and divided communities along sectarian lines.
The government of former President Hosni Mubarak blamed the Salafists, an ultra-conservative Islamic sect.
But others believe the former interior minister was involved. So far no one has been prosecuted for the attack.
Al Jazeera's Jamal ElShayyal reports from Alexandria.