The co-pilot of the EgyptAir Airbus that was hijacked on Tuesday was the last person to remain on board the A320 with the passenger who pretended to have an explosive belt and forced the crew to land in Cyprus. According to the account Hamad el Kaddah gave Newsweek, during the flight from Alexandria bound for Cairo, Seif el-Din Mustafa came out of a bathroom and told a flight attendant he had explosives.
Source: avwebCo-pilot: Hijacker Demanded To Fly Out Of Cyprus