Nigeria's Boko Haram leader Abubakar Shekau, or a man claiming to be him, has been killed at least three times so far, according to the military, yet each time he apparently returns in the group's numerous jihadist videos.
Dead or alive, he appears to be fuelling violence which rights groups say is killing more people than at any time during Boko Haram's five-year-old reign of terror in the north of the 175 million-strong state.