A former manager at a Northwest Philadelphia mental-health treatment facility has admitted that she embezzled more than $600,000 in public funds meant to help children suffering from trauma and behavioral disorders.

Sonja McQuillar, the former director of health and information management at Northern Children's Services, created phony invoices to pay family members, friends, and agency contractors for work they did not perform, federal prosecutors said.

In a hearing Monday before U.S. District Judge Gene E.K. Pratter, McQuillar, 50, of New Castle, Del., acknowledged that she forged signatures to cash the checks and pocketed the money.

Prosecutors said McQuillar stole the money from 2002 to 2014. She pleaded guilty to charges of theft and making false statements to authorities.

Her lawyer, Jose Luis Ongay, did not immediately return calls for comment Tuesday.

McQuillar's theft first came to light through a tip to the Philadelphia Office of Inspector General. The nonprofit's administrators discovered the financial improprieties in June 2014.

Within two years, the agency's financial struggles prompted officials there to issue public pleas for help in funding repairs to a broken boiler, which had rendered some facilities on the agency's Ridge Avenue campus in Wissahickon unusable during the winter.

Administrators have since said that some of the money McQuillar took might have been used to pay for the necessary maintenance.

Northern Children's Services offers residential and outpatient programs that serve thousands of low-income children and families. The agency, founded in 1853 as the Northern Home for Friendless Children, is a regular recipient of federal grant funds awarded by the city and the Philadelphia School District.