DOVER, Del. (AP) — A retired teacher and tennis coach has been charged in sex crimes that police in Delaware say took place nearly three decades ago.

Mark Hoffman with Dover police tells news outlets 73-year-old Carl Fennell turned himself in Wednesday, acknowledging sexual acts with a teen girl he mentored between July 1989 and May 1990. Hoffman says the now-43-year-old woman contacted police July 11 and said Fennell coerced her into performing sexual acts after tennis lessons, which he drove her to and from.

Fennell told police it happened at least 10 times but not more than 20.

Fennell worked in the Capital School District from 1969 to 2001. He was also an assistant coach for the Delaware State University's women's tennis program for three years.

It's unclear whether he has a lawyer.