murdered. >> reporter: tonight, malaysian officials say the only north korean detained in the case is being released from custody and deported. police don't have enough evidence to charge him. three other north koreans believed to be in malaysia are wanted for questioning. the north koreans aren't making them available. four others are believed to be back in pyongyang. >> they don't play by the international rules. >> they characterize the death as a sophisticated operation. that same official says kim jong-un can't be allowed to have a nuclear capability. tonight, another administration official tells cnn there's a review under way for officials to come up with a way to counter kim's weapons threat. military options are always on the table in these discussions. general walter sharp, who