Carey's mother said her daughter suffered from post-partum depression.
The harrowing chase Thursday unfolded between two national landmarks, briefly shuttered the chambers where federal lawmakers were debating how to end a government shutdown and stirred fresh panic in a city where a gunman two weeks ago killed 12 people.
Carey was traveling with a 1-year-old girl who avoided serious injury and was taken into protective custody. The officials spoke on condition of anonymity because they were not authorized to discuss an ongoing investigation.
Carey's mother, Idella Carey, told ABC News on Thursday night that her daughter began suffering from post-partum depression after giving birth to her daughter, Erica, last August.
"A few months later, she got sick," she said. "She was depressed. ... She was hospitalized."
Idella Carey said her daughter had "no history of violence" and she didn't know why she was in Washington on Thursday. She said she thought Carey was taking Erica to a doctor's appointment in Connecticut.
Police said there appeared to be no direct link to terrorism and there was no indication the woman was even armed. Capitol Police Chief Kim Dine, whose officers have been working without pay as a result of the shutdown, called it an "isolated, singular matter."
Still, tourists, congressional staff and even some senators watched anxiously as a caravan of law enforcement vehicles chased a black Infiniti with Connecticut license plates down Constitution Avenue outside the Capitol and as officers with high-powered firearms canvased the area. The House and Senate both abruptly suspended business, a lawmaker's speech cut off in mid-sentence, as the Capitol Police broadcast a message over its emergency radio system telling people to stay in place and move away from the windows.
The woman's car at one point had been surrounded by police cars and she managed to escape, careening around a traffic circle and past the north side of the Capitol. Video shot by a TV cameraman showed police pointing firearms at her car before she rammed a Secret Service vehicle and continued driving. Metropolitan Police Chief Cathy Lanier said police shot and killed her a block northeast of the historic building.
In Stamford, the FBI served a search warrant in connection with the investigation and police cordoned off a condominium building and the surrounding neighborhood in the shoreline city.
Condo resident Eric Bredow, a banker, said police told him the suspect in the car chase was one of his neighbors.
"I see the door to my building open and the FBI bomb squad in front of it," said Bredow, who said helicopters were flying overhead when he first went home.
The chain-of-events began when the woman sped onto a driveway leading to the White House, over a set of barricades. When the driver couldn't get through a second barrier, she spun the car in the opposite direction, flipping a Secret Service officer over the hood of the car as she sped away, said B.J. Campbell, a tourist from Portland, Ore.
"This wasn't no accident. She was not a lost tourist," Campbell said later near the scene that had been blocked off with police tape.