[Atlas Sneezed]

"These people are not using silenced weapons."

I don't think we know that. Inexperienced Marylanders who hear a supersonic crack of a rifle bullet might not miss the muzzle report. If Chief Wiggum (Moose) and his boys were clever, they would do a good job of interviewing the witnesses to discern whether there was the second boom after they heard the crack. Normally, for witnesses far from the shooter, but near the bullet path, you expect stories about "two shots."

[supercat]

Normally, for witnesses far from the shooter, but near the bullet path, you expect stories about "two shots."

Would interviewing witnesses about the relative timing of the "two shots" they heard be perhaps more informative than asking them about apparent sound direction? Even if any witness may be off by a factor of two, enough witnesseses may allow the police to plot out the possible shooter locations that would have produced the perceived sounds.