Is it time to play spy again?

If a friend of my wife's was drugged and almost d. And the police say they can't prove anything should i step in and provide the proof? Guys like this seem to do that as a habit or pattern. I have dealt with problems like this in the past to help provide a "solution" but I promised my wife I wouldn't do that anymore. What should I do? The only thing necessary for evil to triumph is for good men to do nothing.