Details are emerging about Aaron Alexis and his chaotic morning of violence that left 12 people dead at the Washington Navy Yard on Monday. But more questions remain. Here are the latest developments:
• Vice President Joe Biden arrived Wednesday at MedStar Washington Hospital Center to visit those injured in the shooting.
• Damage inside Building 197, the site of the shooting, is significant, according to two Navy officials. There are bullet holes and broken doors and windows. There are also paint markings from law enforcement as they cleared certain areas. "There is blood everywhere. There is damage everywhere," said one of the officials.
• Alexis made unexplained etchings into the shotgun used in the attack, according to a federal law enforcement official. The etchings read "better off this way" and "my elf weapon," the source said. Investigators don't know what the engravings refer to.
• An autopsy on the suspected shooter is expected to be completed by the end of the day Wednesday, according to a spokeswoman for the Office of the Chief Medical Examiner in Washington.
• Alexis received treatment on August 23 when he visited the emergency room at the VA Medical Center in Providence, Rhode Island, according to a statement from the Department of Veterans Affairs. He had complained of insomnia and was given a small amount of medication to help him sleep. On August 28, he went to the VA Medical Center in Washington to request a refill.
• In both instances, the VA statement said, Alexis was asked whether he was struggling with anxiety or depression, or had thoughts about harming himself or others. He reportedly said he did not.
• Tactical officers with the U.S. Capitol Police attempting to help stop the deadly rampage Monday were told by a watch commander to return to their position at the Capitol, CNN has learned. In a statement, the agency said its officers had "offered and provided mutual support and assistance," adding that Chief Kim Dine had opened an investigation.
Mother of shooter apologizes
• Cathleen Alexis, the mother of Washington Navy Yard shooter Aaron Alexis, issued an audio statement on Wednesday.
• "Our son, Aaron Alexis, has murdered 12 people and wounded several others. His actions have had a profound and everlasting effect on the families of the victims. I don't know why he did what he did. And I'll never be able to ask him why. Aaron is now in a place where he can no longer do harm to anyone. And for that I am glad. To the families of the victims, I'm so, so very sorry this has happened. My heart is broken."
Open to essential personnel
• The Navy Yard crime scene continues to be active and is open only to essential personnel, spokesman Ed Zeigler said.
• Access to Building 197 is still prohibited.
Sequence of events
• When Alexis entered the building, he had a small bag believed to have contained a disassembled Remington 870 shotgun, a federal law enforcement official says.
• Alexis was seen on surveillance video ducking into a bathroom with the small bag and leaving with the shotgun.
• He also had "00" buckshot shells, each packed with about a dozen pellets capable of causing tremendous damage.
• Denise Robinson, who works in Building 197, told CNN's "New Day" on Wednesday that she saw the shooter and remembers his "cold stare."
"He looked very calm and composed. He didn't look like a person that was angry or doing that type of event," she said.
Security clearance questions
• Defense Secretary Chuck Hagel announced Wednesday a review of all physical and access procedures at U.S. military installations worldwide as first reported Tuesday by CNN's Barbara Starr.
• Deputy Defense Secretary Ashton Carter has been directed to lead a review of Defense Department procedures for granting and renewing security clearances, including those of contractors, Hagel said. Hagel said that review would be conducted in coordination with other government agencies. He also announced the formation of an outside panel to look at Defense Department security and clearance procedures.
• "Everything possible" will be done to prevent shootings like the one at the Navy Yard "from ever happening again," Hagel said. "Our people deserve safe and secure workplaces."