Mulla Husayn’s brother and nephew were both among the Letters of the Living – they were martyred at Fort Tabarsi

Mírzá Muḥammad-Báqir, the nephew of Mullá Husayn. He, as well as Mírzá Muḥammad-Ḥasan, accompanied Mullá Ḥusayn from Bushrúyih to Karbilá and from thence to Shíráz, where they embraced the Message of the Báb and were enrolled among the Letters of the Living. With the exception of the journey of Mullá Husayn to the castle of Máh-Kú, they continued to be with him until the time they suffered martyrdom in the fort of Tabarsí. 

- Nabil  (‘The Dawn-Breakers’; translated and edited by Shoghi Effendi)