Theresa Lynn Dugan, 22, a 1975 graduate of Northwestern Senior High School in Hyattsville, died Saturday in the Shock Trauma Unit of University Hospital in Baltimore of injuries suffered in a car accident earlier that day in Laurel.

Miss Dugan, a Washington native, was a passenger in the car driven by her fiance, William M. Fallica. They were making a left turn from Maryland Rte. 198 into the Maryland City Plaza parking lot, at about 9:30 p.m., when it was struck by an on-coming car that was operating without lights, according to a spokesmen for the Anne Arundel County police department.

Fallica was treated at a local hospital and released. Miss Dugan was taken by helicopter to the Shock Trauma Unit, where she was pronounced dead at 10:31 p.m. The driver of the second vehicle was not injured. An investigation into the accident is continuing, police said.

Miss Dugan is survived by her parents, Mr. and Mrs. Anthony Dugan, and two sisters, Catherine E. and Mary Jane Dugan, all of the home in Hyattsville; another sister, Patricia Ann Sutton, of Greenbelt, and her grandparents, Mr. and Mrs. Arthur Laughton, of Mount Rainier, and Mrs. Alleda V. Davis, of College Park.