Legal Question in Criminal Law in Massachusetts

THIS IS NOT LEGAL ADVICE AND I AM NOT YOUR ATTORNEY.

You can probably go to the police station and tell them you need to amend a prior statement. I would suggest you try to avoid (if you can) telling them specifically why you need to modify, just that you feel it is important to clarify, add to, alter the prior statement to ensure completeness and accuracy. If you need to say you want to recant, its not the end of the world. Then, tell the truth, the whole truth and nothing but.

Before you talk to the police, I recommend that you discuss the specifics of this with an attorney. While it may not be a big deal to revise some statements a person gives the police, in other instances it may constitute a crime to file a false police report. Without knowing the specifics of your case, it's impossible to know whether your situation is relatively trivial or more significant. A brief consultation with an attorney experienced in criminal law ought to give you useful information about that.