The interstate nature of the crime would mean that the federal government would have become involved in the matter either at the beginning or throughout the process.
During a stakeout at a cemetery, Richard Belzer's character mentions that Montgomery Clift and Walt Whitman were buried in the cemetery. Clift is buried in Prospect Park in Brooklyn and Walt Whitman is buried in Camden, NJ.
The Janaways' neighbor in Maryland has a strong New York accent, very different from the distinctive Baltimore accent.