Fred Preston, 70, has died in a London, Ont., hospital after a shootout that left an OPP officer dead. (backyardstuff.ca)

Fred Preston, who faced charges in the shootout death of an Ontario Provincial Police officer, has died, the province's Special Investigations Unit confirmed late Thursday.

Preston, 70, had been in critical condition in London's Victoria Hospital after being shot several times in a shootout on a rural road near the community of Seaforth in southwestern Ontario.

Relatives of Preston said he died in the evening after he was taken off life support.

Const. Vu Pham, 37, of the Ontario Provincial Police, was fatally shot Monday near Seaforth, Ont. (OPP/Canadian Press)

The confrontation killed Const. Vu Pham, a 15-year OPP veteran, who was shot and killed Monday after pulling over a pickup truck on a rural southwestern Ontario road.

Preston was then wounded in an exchange of gunfire after another officer got to the scene near Wingham, Ont., north of London. Preston was charged Wednesday with first-degree murder in the death of Pham and attempted murder regarding the other officer.

Pham died several hours after being flown to London's Health Sciences Centre, with his wife and three children at his side.

Hundreds of people lined up around the block outside the McBurney Funeral Home at the visitation for Pham in Wingham Thursday night. Thousands of police officers are expected to attend Pham's funeral Friday.

Preston was a former Ontario township council leader who was struggling with marital problems. The father of three grown daughters, he was the reeve of Joly Township on the western edge of Algonquin Park from the 1990s until 2003.

Sources said Preston's wife left him last fall and moved in with their youngest daughter in southwestern Ontario. Police believe Preston was on his way to see his wife when he was pulled over by the OPP.