The police are responsible...is the correct one. Also, no article before the verb capture and use the verb catch instead. I mean, it's The police are responsible for catching criminals.
The verb capture in this context is perfectly fine. Catch and Capture are slightly different, yet both fit well in this case. Capture is in fact a more appropriate and formal term, representing a higher level of language. So, you may either say: The infamous gang leader was quickly captured this morning by the mobilized local police; or,