Police have identified the pedestrian killed Tuesday in Topsham as Margaret Reid, 38, of Corte Madera, California.

Police say Reid was walking eastbound on Route 196 with her 6-year-old son around 10:24 a.m. on Dec. 7 when she was struck from behind by a 2006 Subaru Impreza driven by Jorge A. Rodriguez-Ramos, 35, of Brunswick.

Rodriguez-Ramos’ car was traveling east when it crossed the centerline and passed through the westbound lane, striking Reid on the side of the road, according to police.

Police say they believe Rodriguez-Ramos fell asleep while driving home from work after an overnight shift.

Reid was flown by helicopter to Central Maine Medical Center in Lewiston where she died of her injuries, police say.

Reid’s son was not injured.

“Her son seems to be doing fine,” said Topsham Police Chief Marc Hagan. “I spoke to his grandfather and everybody is still in shock. They are trying to comprehend what happened.”

Rodriguez-Ramos was treated and released from Maine Medical Center in Portland on the day of the crash.

Hagan said Reid, along with her parents and son had been visiting her sister in Topsham, and her family has since returned to California. He declined to provide more details.

“All agencies involved in this tragic event again offer their heartfelt condolences to the family and friends of Margaret Reid,” Hagan wrote in a prepared statement. “We would also like to take a moment to thank those who stopped to offer assistance to Mrs. Reid and her son.”

The Sagadahoc County District Attorney’s Office is now investigating the incident to determine whether there will be any criminal charges.