Today, the Navy Yard returns to normal operations three days after 34-year-old Aaron Alexis allegedly went on a mass shooting spree that claimed the lives of 12 people and injured eight.

The Associated Press reports that all the facilities of Navy Yard will be reopened, with the exception of Building 197 and the base’s gymnasium.

Navy spokeswoman Lt. Cmdr. Sarah Flaherty said Thursday will be a regular work day, except for Building 197, where the shootings occurred, and the base gym. She says the gym is being used as a staging area for the FBI to investigate Monday’s rampage in which former Navy reservist Aaron Alexis gunned down 12 people before being killed by police.

But of course, returning to normalcy at a shooting site three days after it occurred isn’t easy for most employees. Some employees told the AP that they’re “still unsettled” about returning to work and that things are “still not quite normal,” and that “it probably won’t be for some time.”

As employees return to work, the FBI is still trying to determine a motive as to why Alexis went on a murderous rampage at the Navy Yard facilities. Reports have surfaced that Alexis had been suffering from paranoid delusions and other symptoms of severe mental illness. He even visited two VA hospitals to seek treatment for insomnia, but did not indicate that he was suffering from depression, anxiety, or any thoughts of harming himself or others.

As the investigation into the the events prior to Monday’s shooting continues, more details are coming to light about Alexis’ fragile mental health state. According to authorities, Alexis etched two phrases into the sides of the shotgun he used in his rampage: “better off this way” and “My ELF weapon.” The FBI is still unsure as to what the second phrase could refer to.

But there are some theories as to the meaning of the phrase. According to The Week, it could stand for “extremely low frequency,” which the Navy has used in different research programs.

The Navy has used extremely low frequencies in a program with the Air Force called the High Frequency Active Auroral Research Program (HAARP), an ionospheric research program often cited by conspiracy theorists as a tool used by the government to trigger natural disasters.

A DCist reader tips us off to another potential theory that the phrase is a reference to a Marvel Comics villain called “Elf with a Gun,” who is “a small humanoid who commits murders for no apparent reason.”

Meanwhile, WJLA reports that the Capitol Police, who were among some of the first responders, are investigating claims that a team was told to “stand down” during their early response to reports of the shooting.

According to a statement from Capitol Police Lt. Kim Schneider, Police Chief Kim Dine has “opened preliminary investigation into the allegations” that a supervisor told a Capitol Police CERT team to stand down and not engage the shooter as an early response to the active shooter situation unfolding at the Navy Yard Monday.

Congresswoman Eleanor Holmes Norton (D-DC) will meet with the Capitol Police Union “in the near future” in regards to the investigation that the tactical team was initially told not to proceed in engaging Alexis, according to a press release.

Norton believes an investigation is necessary to determine whether other tactical police forces were on the scene or available, whether lives could have been saved by Capitol Police without putting the Capitol at risk, and if there was proper coordination of police forces.

With multiple agencies responding to Monday’s shooting minutes after it was first reported, the communication between these agencies remains a problem. According to a press release from the International Association of Fire Fighters, some local IAFF members were among the first responders:

But direct communication with other agencies remains a challenge. Local F-121 President Greg Russell says, “Our radios still do not communicate with every agency,” he explains. “This is a big safety concern.”

During the police’s response and engagement of Alexis, officer Scott Williams was shot and critically injured, but is reportedly in good condition and in high spirits. At a press conference on Tuesday, Metropolitan Police Department Chief Cathy Lanier said that he’s in good health and is “confident” he’ll make a full recovery.