The California Highway Patrol is seeking the public’s assistance in finding a motorcycle rider who left the scene of a crash Thursday afternoon. CHP Officer Joan Griffin said at 1:15 p.m., Christian Giangreco, 43, was preparing to back his Subaru Crosstrek into his driveway in the 61700 block of Alta Mura Drive in Joshua Tree, when a man heading eastbound at a high rate of speed on a white dirt bike hit Giangreco’s Subaru as he tried to pass it. The man was thrown off his bike. Griffin said Giangreco checked on the rider, then said he was going to call the police, at which time the man got back onto the dirt bike and rode off north on Sunset Road. The motorcycle rider is described as a white man in his 20’s, wearing a red shirt and a black and white helmet. Anyone with information on the identity of the rider is asked to call the CHP at 760-366-3707.