If this BBC News story is true, then Capitol Police officials are de facto accessories to murder:

Multiple sources in the Capitol Police department have told the BBC that its highly trained and heavily armed four-man Containment and Emergency Response Team (Cert) was near the Navy Yard when the initial report of an active shooter came in about 8:20 local time.

The officers, wearing full tactical gear and armed with HK-416 assault weapons, arrived outside Building 197 a few minutes later, an official with knowledge of the incident told the BBC.

According to a Capitol Police source, an officer with the Metropolitan Police Department (MPD), Washington DC’s main municipal force, told the Capitol Cert officers they were the only police on the site equipped with long guns and requested their help stopping the gunman.

When the Capitol Police team radioed their superiors, they were told by a watch commander to leave the scene, the BBC was told.

The gunman, Aaron Alexis, was reported killed after 9:00.

HK-416s are a variant of the M4 carbine, and the Capitol Police CERT unit is basically a fire-team specializing in dynamic entry and close-quarters battle in fluid situations where target discrimination is paramount. If this Capitol Police CERT unit is trained to even a  fraction of a degree one would expect,  then they would have greatly over-matched mass-murdering Alexis, a glorified electrician with the infantry combat experience of a Cub Scout.

If it is determined that the Capitol Police CERT team were forced to stand down by a supervisor because of some petty jurisdictional turf war, then heads should roll.

Update: A previous version of this story incorrectly stated that a Metro Police supervisor told the CERT Team to stand down. Instead, it was a Capitol Police watch commander that allegedly told the unit to stand down.