CNN, citing a source close to the investigation, said a search of the apartment in Stamford, Conn., where Carey lived with her year-old daughter turned up medication for schizophrenia and bipolar disorder and an anti-depressant.
Carey had a child with her when she attempted to get through a White House perimeter checkpoint Thursday. The child survived the chase and shooting unharmed.
Carey's boyfriend, the father of her child, told authorities in December he feared for the little girl's safety, CNN said, citing another source. He said Carey was delusional and had told him President Obama had locked down Stamford and she was being monitored electronically.
The chase Thursday afternoon prompted a lockdown at the Capitol, and directives that members of Congress shelter in place. Streets ringing Capitol Hill were cordoned off.
Carey, 34, was a dental hygienist living in Stamford, Conn. Dr. Barry Weiss told NBC Carey was working in his dental office in 2012. He said he fired her after patients complained she was too rough.
Dr. Steven Oken, a New York dentist who employed Miriam Carey for eight years, told ABC he "would never in a million years believe that she would do something like this."
"It's the furthest thing from anything I would think she would do, especially with her child in the car. I am floored that it would be her," he said.
Carey was driving a black Infiniti when she rammed a perimeter security barrier around the White House. She left after striking a Secret Service officer with her car.
Police said she then sped along Pennsylvania Avenue toward the Capitol with speeds exceeding 80 mph. Police and the Secret Service stopped her near the Capitol, but she put the car into reverse and sped away as police opened fire.
Carey led police on a chase and crashed her car outside the Hart Senate Office Building several minutes later, police said. Officers fired at her, and she died soon after.
A Capitol police officer was hurt as he was speeding to confront her and his patrol car hit a barrier that popped up in the street.
Carey's mother said her daughter was suffering from postpartum depression, ABC News said.
"She got sick" a few months after giving birth to Erica, said Idella Carey said of her daughter. "She was depressed. ... She was hospitalized."
She told told ABC her daughter had "no history of violence."
The incident occurred 2 1/2 weeks after the Washington Navy Yard shooting that killed 12 people and injured three others.
"This appears to be an isolated, singular matter, with, at this point, no nexus to terrorism," Capitol Police Chief Kim Dine told reporters.