Why was this case tried in a court-martial?

A U.S. Coast Guard Academy cadet has been convicted of a sexual assault committed in Pennsylvania. The case was initially investigated by local police in Westchester, PA. The Academy is located in New London, Connecticut. According to this New London Day report:

The Coast Guard took over jurisdiction of the case after people expressed concerns about [Michael] Shermot's military status and about some of the witnesses involved in the case.

The usual question: why wasn't the case tried locally? The Day's account is uninformative.