Looks like the shooter outfoxed Moose & Co. Moose thought this would be just like the movies. The guy calls, they trace his call. SWAT teams swoop in and viola Moose for DC mayor!
Moose isn't quite up with times. The shooter probably called from a stolen cellphone, an untraceable hotmail account\stolen credit card via Net2Phone or, an overseas accomplice called.
And now Moose wants him to call back...as the message was garbled...and the press ran with it as the truth.