My theories are:
1. The gangster Mistu could be a doppelganger.
OR
2. The gangster Mistu is the present "Mistu" from the past and was coerced into some sort of cult (hence the cross on the female victim's neck and on the wrist of terrorist journalist guy. When he escaped, he vowed to get rid of the said cult, this would mean killing the followers and the leader. But the leader, who we shall assume to be the terrorist, wants to continue to spread his preach and thus is trying to kill Mitsu as well. This is all far fetched, but it's something to fill in the gaps for now.