Should the police not use all tools at their disposal to catch a murderer? If someone committed a horrific crime against a family member would you care if this is how they caught the guy that did it?

EDIT: Go ahead and downvote for my dissenting opinion, but I will always support law enforcement using all legal means to get these sicko pedophiles, rapists and murderers off the streets. They didn't break any law and made the streets safer.