Write down, in detail, everything you did (where you were, who you were with) over a forty-eight hour period when the crime allegedly occured.
Ask the people who were with you to write a statement (affidavit) detailing their time with you during that period (establish an alibi).
Obtain an attorney and bring these with you. He will, most likely interview you and the alibis (recount their statements in front of him/her).
Now my question is, why would you assume you will be accused of a crime you didn’t commit? Do you associate with the folks who did commit it? Do you have a record? Is this a vendetta?