Read: Whistleblower says officials considered using "heat ray" on D.C. protesters

Federal officials stockpiled ammunition at the D.C Armory and sought crowd control devices before law enforcement forcibly cleared protesters from Lafayette Square in June, a whistleblower said in written submissions to Congress.

Why it matters: D.C. National Guard Maj. Adam DeMarco's testimony is a part of a congressional investigation into law enforcement's use of force against demonstrators protesting George Floyd's death in the square.

• DeMarco alleges that military police asked the National Guard if they had an Active Denial System (ADS), or military" heat ray," which they could use.

Context: "Developed by the military as a crowd dispersal tool decades ago, the ADS has largely been abandoned amid doubt of its effectiveness and ethical questions," USA Today notes.

Background: Federal forces flushed protesters from the park across from the White House on June 1, deploying tear gas, stun grenades and brute force, shoving demonstrators and members of the media with shields and batons.

• They did so shortly before President Trump crossed the park to pose for photos with a Bible at St John's Episcopal Church — across the street from the square.

The big picture: The Trump administration argued afterward that protests had turned violent and officers were responding to fireworks, fires and thrown water bottles and rocks.

• DeMarco testified in July that the use of force was an "unnecessary" and "unprovoked" escalation that he and his fellow National Guardsmen viewed as "deeply disturbing."
• He said assault rifles were transferred from Fort Belvoir to the D.C. Armory on June 1 and that transfers of ammunition from states such as Missouri and Tennessee arrived in subsequent days.
• By mid-June, about 7,000 rounds of 5.56 mm and 7.62 mm ammunition rounds had been transferred to the D.C. Armory, DeMarco said, though he did not specify that the rounds may be used for.
• The Trump administration did not immediately return Axios' requests for comment.

Read DeMarco's written response, obtained and shared by NPR, via DocumentCloud: