You are not required to sign a statement. If subpoenaed to testify in court, however, you will be required to do so. If you refuse, you could be held in contempt and sent to jail until you change your mind. If you give testimony different from what you told the police the first time, you could face either a perjury charge or a charge of providing false information to a police officer. You are a little late in your desire not to get involved.
This answer is provided for educational purposes only and is not intended as the practice of law in any jurisdiction in which I am not licensed. The answer does not constitute legal advice nor does it create an attorney-client relationship. The answer is based only on the information provided, and may be inaccurate in the context of additional facts that have not been provided. The questioner should be aware that I am only licensed to practice law in the state and federal courts of Minnesota. Accordingly, before taking any action or refraining from taking any action, the questioner should consult with an attorney licensed to practice in his or her jurisdiction.
"Change your mind" = possibly perjure yourself if called to testify in court? Hire a locally experienced criminal defense attorney to represent you to make sure you don't continue to dig yourself deeper into this mess.
Law Offices of David Shapiro 3555 4th Avenue San Diego, CA 92103 (619) 295-3555