Boko Haram kills kidnapped CAN chairman, Rev Lawan Andimi 15 days after he was abducted .
Ahmad Salkida, a journalist with years of experience reporting the activities of the insurgents, in a series of tweets said Andimi was killed on Monday .
Andimi was abducted early January when the insurgents attacked his village. Days after his abduction, the clergyman, in a video clip released by the insurgents, asked the Governor of Adamawa to rescue him.