A St. James man struck by a car while riding his motorcycle in Mattituck last month has died from his injuries, Southold Town police said Monday.

Detectives handling the case learned Friday that Patrick Lonergan, 56, seriously injured in the accident on March 20, had died, Police Chief Martin Flatley said.

Southold police said Lonergan was hit by a 1999 Oldsmobile sedan driven by Lucretia Kramer, 85, who made a left turn from westbound Route 48 onto Wickham Avenue.

Kramer turned into the path of Lonergan, who was on a 2013 Harley-Davidson going east on Route 48, police said.

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Lonergan was taken to Stony Brook University Hospital.

Kramer, of Mattituck, and her passenger Barbara Judge, 71, of Brooklyn, were taken to Peconic Bay Medical Center in Riverhead with head and neck pain. Kramer was issued traffic summonses for failing to yield the right of way and failing to comply with restrictions on her license, police said.

Flatley said Monday that the case, as with any motor vehicle fatality, would be sent to the Suffolk County district attorney for evaluation.