need help asap

[aia123]

i was recently arrested for criminal mischief to(i am being accused of tearing down a street sign) and i wasnt even at the place where the sign was. we apparently matched the description of the suspects, i was wondering if this was legit. also, if the kids who actually did it admit it will i still b charged? is it worth getting a public defender for fighting this(its a misdemeanor) or should i just sit by and take the punishment for a crime that i was not involved with