A 16-year-old boy shot by police in Brooklyn two months ago lay mortally wounded on the ground for 15 minutes before getting medical attention, according to the teen’s family.

The parents of Kimani Gray are expected to file a notice of claim Wednesday, informing the city of their intent to file a wrongful-death lawsuit that alleges police used excessive force in the March 9 shooting.

Family lawyer Kenneth Montgomery said he can prove NYPD cops left Gray to die in East Flatbush.

“We have a videotape that shows all these police personnel who pretty much militarized the block,” he said. “And this young man is on the pavement, perceived not to be getting any medical attention for up to 15 minutes.”