Miriam Carey was a 34-year-old dental hygienist who lived in Stamford, Conn.
Her former boss of eight years, Dr. Steven Oken, told ABC News that he was "floored" that she would do something like this.
A subsequent employer, Dr. Barry J. Weiss, noted that she had trouble getting along with with other employees, however, which may have contributed to her getting fired in August 2012.
"When we confronted her about certain situations within the office, she had a temper," Dr. Weiss told the New York Times.
She moved from Brooklyn to Stamford because she could not afford her rent and had problems with her landlord, a friend told The Washington Post.
Carey had no history of violence. She may have had mental health issues, though.
Authorities reportedly found medications that treat schizophrenia and other mental disorders in Carey's
Carey reportedly suffered from postpartum depression after the birth of her daughter, her mother, Idella, told ABC News. Idella said: "A few months later, she got sick. She was depressed. ... She was hospitalized."
Her boyfriend contacted police in December saying he feared for the safety of their infant child,
She also sustained a "pretty significant" head injury recently after falling down stairs, her former boss told the New York Daily News.
Carey might have thought President Barack Obama was stalking her, law enforcement sources told NBC News.
Carey was shot and killed after running into a barrier and hitting a Secret Service officer at the White House. Police pursued her car to
She had her 1-year-old daughter in the car with her during the pursuit.
Carey's relatives in Brooklyn, N.Y. are reportedly refusing to speak with investigators, CNN reported.