Eugene Ciardullo, of Chicago's Far Southwest Side, was employed as a part-time security guard at a school where the victim was enrolled, police said. Chicago Public Schools confirmed that he worked for Chicago High School for Agricultural Sciences, but was removed from his position in December "in response to serious allegations."
The victim, now 18, told police that she had a sexual relationship with Ciardullo when she was 17.
Ciardullo, a 21-year Chicago police veteran assigned to the 9th District, was stripped of his police powers.
He was arrested without incident Saturday afternoon at his Scottsdale neighborhood home, police said.