reporter: this man muhammad al-mahoud is said to be a schooltrech in gris a. according to police, they believe he s a mastermind of the attack. he wanted for other attacks in kenya, including the westgate attack, as well. he s said to have been a collaborator, and those who know him say he was a teacher in garissa and was quite strict in his teachings and his faith and beliefs. now he has climbed the ranks in al shabaab, and that s why the police want him. initially they issued an alert for him in the previous years, $5 million. now they ve increased it five million shillings to over 200 million shillings for information leading to his arrest. we know that they shot and killed four militants to try and