He was, however, killed that same day by the Qizilbash tribes that favoured his brother Ismail Mirza Safavi as the successor of their father.

The Rumlu, Afshar and Qajar clans favoured Ismail Mirza Safavi, who was jailed in the Qahqaheh Castle.

[3] While Tahmasp was still ill, those who supported Haydar Mirza sent a message to the castellan of Qahqaheh Castle, named Khalifa Ansar Qaradghlu.

Tahmasp, who still favoured Ismail Mirza because of the courage he had had shown in battles with the Ottoman Empire, sent Afshar musketeers to the Qahqaheh Castle to protect him.

[3] When Haydar Mirza found out about the dangerous position he was in, he took Pari Khan Khanum (who was also in the palace) "into custody as a precautionary measure" (Parsadust).

[3] Pari Khan Khanum then "threw herself at her brother's feet in the presence of Haydar Mirza's mother", and tried to urge him to let her leave the palace, stating that she was the first to acknowledge his rule by prostrating herself in front of him.