Purity: Ghusl for Touching a Corpse
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 510:
If someone touches – i.e. makes part of his body come into contact with – the body of a dead person after it has become cold but before it has been given ghusl, he must perform the ghusl for touching a corpse, irrespective of whether he touches it while he is asleep or awake, voluntarily or involuntarily. Even if one’s nail or bone touches a nail or bone of the corpse, he must perform this ghusl. However, if one touches a dead animal, performing ghusl is not obligatory for him.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)