AUGUSTA — A 21-year-old single mother was sentenced to serve three months in the county jail Thursday for faking an armed robbery last October at a McDonald’s restaurant in Waterville and keeping the money for herself.

Lisa Didas, whose daughter Jasmen turned one last month, will also enroll in a residential treatment program in Portland once she is released from custody, and must perform 100 hours of public service at area high schools for each of her two years of probation.

Didas, who was valedictorian of her 2004 graduating class at Averill High School at Good Will-Hinckley, said substance abuse was her downfall.