Police have arrested a Medford man for driving while ability impaired by drugs in a crash that killed a motorcyclist in Islandia.

Alan Mercado, 67, was driving a 2010 Honda westbound on the Long Island Expressway just east of Exit 57 when he attempted to move from the center to the right lane and was struck from behind by a motorcycle at 1:12 a.m.

The motorcycle operator, who is not being identified pending notification of next of kin, was pronounced dead at the scene by a physician assistant.

A passenger in the Honda was transported to South Shore University Hospital in Bay Shore for treatment of injuries not considered life-threatening. Mercado was not injured.