Zarqawi's successor imprisoned in Egypt?!

The debate around the identity of Zarqawi's successor is getting really "Kafkaesque" as Arabist reader SP wrote me in an email exchange.
Now Islamist lawyer, and former Egyptian Islamic Jihad activist, Mamdouh Ismail is saying Abu Ayub al-Masri, Zarqawi's alleged successor, actually is and has been in an Egyptian prison for the past seven years.
This comes after Islamist lawyer Montasser al-Zayat suggested he was another man by the name Youssef al-Dardeeri, while London-based Egyptian Islamist exile, Yasser al-Sirri, claimed the man did not even exist.