The investigation into a fatal head-on collision in Wiscasset on Friday could take several weeks to complete before the Lincoln County District Attorney will determine whether to file charges in the death, police said Monday.

Alice Barstow, a passenger in a 2006 Lincoln Town Car, was killed when a silver 2011 Volkswagen Jetta crossed the centerline and hit the Lincoln head-on.

Both drivers are still under medical care and have not been interviewed, said Wiscasset Interim Chief Jerry Hinton, who identified the driver of the Jetta as 65-year-old Jiri Slosar of Lexington, Massachusetts.

Slosar was in critical condition at Maine Medical Center in Portland, Hinton said. The driver of the Lincoln, Henry Barstow, 83, of Bristol, was listed in satisfactory condition.

Hinton said both cars will undergo so-called vehicle autopsies, in which state police comb carefully through them to determine whether the mechanical condition of the vehicles may have contributed to the crash.

It is unknown whether the occupants of the vehicles were wearing seat belts, Hinton said.

Multiple agencies, including the Lincoln County Sheriff’s Office and the Maine State Police, are aiding in the investigation, he said.

The crash shut down Route 1 in Wiscasset for several hours as investigators gathered data and evidence in their ongoing effort to reconstruct the crash.

Included in the investigation will be analysis of blood samples taken from the drivers to determine if any biological conditions or drugs or alcohol contributed to the wreck, Hinton said.