The letters -- which were sent to eight House Democrats who represent the New York City area and possibly to other members as well -- reportedly included the words "We did it," a photo of someone standing in front of the recruiting station and what one source called a "20-page rambling rant."
Capitol Police alerted congressional offices about the missives Thursday night, asking that any members who received one to "immediately contact the USCP Command Center" as part of an "ongoing criminal investigation."
But as the Associated Press is now reporting, law enforcement officials believe the person who sent the letters to members of Congress is an anti-war activist from the Los Angeles area who seems to have had no connection to the explosion at the military recruiting facility.
"It was just an incredibly unbelievable coincidence," one law enforcement official tells the AP.
Capitol Police said Thursday that, while the letters sent to members of Congress contained "a reference to the military recruiting office in New York City," they did not make "any threat to the congressional community or members of Congress."
According to the AP, law enforcement officials do not intend to file charges against the man who sent the letters.