A monster who allegedly raped a 12-year-old girl — after he posed as a cop and lured her into his car — turned himself in to police Thursday afternoon, sources said.

Carlos Medina, 51, flashed a law enforcement badge when he approached the child while driving his black SUV on Elder Avenue in the Soundview section of the Bronx around 10:30 p.m. Friday, according to police sources.

After convincing her to get in his car, Medina drove to the Pelham Bay neighborhood, where he attacked her, authorities said.

She was rushed to a nearby hospital after he let her go, cops said.

Cops had released surveillance video shots of him smoking a cigarette, wearing a black jacket, black shirt and a gold necklace.

Medina turned himself in to the NYPD’s Special Victims Division in the Bronx and was charged with two counts of rape, predatory sexual assault, criminal sex act, criminal impersonation, acting in a manner injurious to a child and sexual abuse, cops said.