You obviously don't have 'proof beyond a reasonable doubt'.  And given the way you stated the case there is substantial reasonable doubt just in the way you presented it.  If you went after someone else illegally, well, you are just going to have to deal with the consequences that go along with those actions. 

Additionally, engaging in such illegal acts SEVERELY curtails your credibility in any sort of other case against the individual and ensures that such a case can never be prosecuted because there will never be the credibility to overcome the reasonable doubt standard.  Congratulations you just admitted to SPIKING the chances of the DA ever getting a conviction against the guy.   Dummy.