Law enforcement officials in Washington, D.C., have identified the deceased suspect in the Navy Yard shooting, a violent rampage at the Naval Sea Systems Command Headquarters on Monday that reportedly claimed the lives of at least 13 people and wounded more, as Aaron Alexis. According to CBS News, Alexis was a 34-year-old civilian contractor from Fort Worth, Texas.

It's not yet clear how Alexis died, or what his motive may have been. Officials said they identified Alexis using fingerprints taken from his body, the Wall Street Journal reported.

Earlier on Monday, CBS and NBC misidentified Alexis, allegedly due to an ID card found on his body that belonged to someone else. Both news outlets later retracted their reports. NBC later reported that the ID reportedly belonged to a man who had previously been employed at the Navy Yard. Pete Williams alleged that the ID card was discovered next to Alexis’ body in Building 197, where most of the shooting took place.

The Associated Press reported that the suspected shooter was identified by two federal law enforcement officials who spoke to the publication on the condition of anonymity. At least one of those sources said that Alexis, believed to have recently begun working at the Navy Yard, had a criminal record in Texas. At least one source also told AP that Alexis likely had a concealed-carry weapon permit.

According to the Star-Telegram, Alexis, who friends describe as "polite," was arrested in 2010 for "discharging a firearm within a municipality." The report says that police were called to an apartment on Sep. 4, 2010, after receiving a report that a man had fired shots through the floor and ceiling of a woman's apartment. The report states that the woman had been sitting alone in her apartment when she heard a "pop" and saw dust. 

“[The woman] then saw that there was a hole in her floor just a couple of feet from where she was sitting while shredding papers and a hole in the ceiling... She told me that she believed someone had shot a bullet through her apartment," the report states.

Although the woman told police she was sure Alexis had intentionally fired the shot, and was "terrified" of him, he denied those claims, telling police he had been cleaning his gun when it accidentally discharged. The report states that, “[Alexis] said that he was trying to clean his gun while cooking and that his hands were slippery. He told me that he began to take the gun apart when his hands slipped and pulled the trigger, discharging a round into the ceiling.”

Documents released on Monday by police revealed that Alexis was also arrested in Seattle in 2004 after he fired shots into the rear tires of a car owned by neighborhood construction worker. According to the incident report, no one was injured at the time of the shooting. Alexis reportedly fired a Glock 30 .45 caliber pistol at the worker's car during, what he told police was, a “‘black-out’ fueled by anger.”  The officer who filed the report stated that Alexis told police he did not have any memory of firing the shots until roughly an hour later.

The police documents further alleged that Alexis told police that he believed the worker had "mocked" him earlier in the day, and additionally that he had been "present during the tragic events of September 11th, 2001" and had been "disturbed" by them. He was consequently booked for Malicious Mischief, but apparently never charged in court.

Police have yet to confirm the number of total shooters, but Chief of Police Cathy Lanier said earlier that police had reason to believe there were two more potential suspects. "Right now we have multiple pieces of information that would suggest we have at least two other individuals that were seen with firearms," she said.

Police now say that at least one other gunman may still be on the loose. On Monday afternoon, Lanier announced that the FBI would be taking over the investigation from that point rforward.

President Obama addressed the shooting during a scheduled speech on the financial crisis, saying: “So we are confronting yet another mass shooting, and today it happened on a military installation in our nation’s capital. It’s a shooting that targeted military and civilian personnel. These are men and women going to work, doing their job protecting all of us. They’re patriots, and they know the dangers of serving abroad, but today they faced the unimaginable violence that they wouldn’t have expected here at home."