reference to the great Bornu Empire -- a Muslim kingdom that ruled northern Nigeria for some 500 years -- harks back to a golden age. He is also ruthless in dealing with dissent. Shekau has no deputy and Zenn says that videos issued by the group never show other commanders. He kills anyone who challenges him, but to blow him off as a madman would be to underestimate his capabilities, says Zenn. Twice wounded himself -- in 2009 and 2012 -- Shekau appears to revel in violence. After a series of attacks in Kano in 2012, he said: I enjoy killing anyone that God commands me to kill, the way I enjoy killing chickens and rams. Nor would Zenn be surprised if Shekau were under the influence of drugs when he recorded his video statement; they have sometimes been found in Boko Haram camps by the Nigerian military. ' I said I would... ' The mass abduction of teenage girls yet again delivered on a threat that Shekau has made repeatedly. Western education is a prime target of Boko Haram because in the group's view, it reinforces colonial and Christian influence and suppresses Islam. In a July 2013 video, Shekau promised that schools would be burned and teachers killed. He has been true to his word. In February, a school in Nigeria's northern Yobe state was attacked and burned down, leaving 29 boys dead. And last September, more than 40 students at an agricultural college were killed. In