THE BRONX - Sources tell News 12 that the woman who was shot to death in Washington, D.C. yesterday after attempting to drive through a security barricade at the White House had worked in the Bronx as a dental hygienist for eight years.

The woman, Miriam Carey, worked two days a week at Dental Implants and Periodontics on Pelham Parkway and was last at work on Tuesday.

Investigators say Carey's boyfriend told them she believed President Barack Obama had placed her under surveillance and ordered a lockdown of her hometown of Stamford, Conn.

Carey's mother told ABC News that Carey was suffering from postpartum depression after having her baby.

Carey's coworker also said Carey suffered from postpartum depression, but said she had been better in recent months.

Dr. Steven Oken, Carey's boss, said she was a hard-working and educated woman. He said he too was shocked when he learned what had happened.

Carey was raised in Brooklyn before moving to Connecticut. She graduated from Hostos Community College in 2002 with an associate's degree in applied science.