A pedestrian and a motorist were killed Monday in separate freeway accidents, police said.

Michigan State Police said Roy Laurence Pegouske, 76, was killed about 5 p.m. on northbound Interstate 75 in Woodhaven, about 15 miles south of Detroit, after being struck by a semi truck. Pegouske was reportedly suffering from Alzheimer's disease and wandered onto the freeway from a construction site.

In an unrelated incident, an unidentified motorist was killed and three others injured in a rollover accident on westbound I-94 in St. Clair Shores, about 10 miles northeast of Detroit. The accident, which occurred around 7:30 p.m., forced traffic to back up for miles, state police said.

Police told Detroit television station WDIV that Pegouske had been interested in the construction taking place on a nearby I-75 overpass and had visited the site earlier Monday with his wife. He later returned to the overpass alone before walking out into traffic.

The state police trooper who first arrived on the scene was Pegouske's daughter-in-law, the station said. She traveled with her father-in-law to a nearby hospital, where he was pronounced dead.

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