Did the police capture the right guy? Is he the Man on the Phone and/or the Beast?
I doubt it. Jack Childress is definitely a cop killer and deserves to be imprisoned, but he's not the guy they have been hunting. Sonya and Marco were tricked into following a false lead left by the real Beast.
Last Wednesday, in "ID," the police were investigating a fake police cruiser that was left outside Gina's house after her father was killed. Up until then, the Beast and the Man on the Phone (I still believe they are two different people, though Gina's father could have been killed by either of them.) have been careful not to leave any clues to their identities behind. The police cruiser was left on purpose to mislead the police.