In Untraceable , Marsh tries to catch the murderer because he believes the government should have done something .
Dowd was killed because he came close to the truth of who the murderer was and Marsh was targeted because she was trying to catch him ( and was able to identify and locate him – ruining his fun/vengeance ) , as well as because he feels that the government should have done something , instead of letting the press exploit the tragedies of others .
Untraceable