Question: A player discarded a 9 Crak and another player used it for an exposure. That exposure resulted in their hand being declared dead. Can another player now use the 9 Crak if they need it?

Answer:
No. Once a discarded tile has been claimed and used in an exposure, it stays with the dead hand and cannot be reclaimed by another player.
The only exception is if two players attempt to claim the same tile for Mah Jongg, and the first claim results in a Mah Jongg in Error. In that case, the next player who needs the tile for a valid Mah Jongg is entitled to it. See ID121. 

Source: Mah Jongg Made Easy Edition 2024, pg. 31, para. 4