I have an important question I hope everyone here will reply their opinion.

Is lying okay for a christian to do even if it is for the greater good?

For example, I knew this one catholic girl who worked for a child model site.
She worked to categorically log and monitor the child model industry manufacturing images of little girls out of russia.
Her site attracted nothing but pedophiles who she treated nicely and with dignity, but she would lie to the people and tell them she was attracted to girls and loved them (not exactly a lie but an exaggeration because it was not sexual arousal, although she would lead others to believe so).

Then when she came upon dangerous pedophiles, for example one guy who was dying of a brain tumor confessed to her his lifestyle and she and her crew monitored him very closely for information which once it became prolific and useful enough delivered it to law enforcement, in a different country even!

So, she is lying, but doing it for the good of saving children's lives.
My question is, is it okay for a christian to pose as a decoy this way?

My opinion is no, it is not okay. Although I respected her and loved her as a person, I could not see what she was doing was righteous in the eyes of the lord because she's using deceit to entrap a person possessed by demons.

What is your opinions on this please.