NEW : Taliban source : Bowe Bergdahl 's release would be taking an `` enormous risk '' if they return to the battlefield , Secretary of State John Kerry told CNN in an interview that aired Sunday . `` I 'm not telling you that they do n't have some ability at some point to go back and get involved ( in fighting ) . Mullah Omar has been killed in a drone strike. NEW : Law enforcement official : Threats to Bergdahl family came via e-mail . John Kerry says released Taliban figures will be monitored . If they turn to violent ways , they could die violent deaths , he says .
NEW : Taliban source : Mullah Omar has been killed in a drone strike. NEW : Law enforcement official : Threats to Bergdahl family came via e-mail . John Kerry says released Taliban figures will be monitored . If they turn to violent ways , they could die violent deaths , he says .