Cary, N.C. — Authorities investigating an alleged sexual assault on a child on the campus of Cary Academy named the suspect Wednesday and asked for the public's help in finding him.

Cary police said Alfredo Martinez Lopez, 36, of the Wynslow Park area of Raleigh, is wanted in connection with the crime, which happened about 7:30 p.m. Friday on the grounds of the private school.

According to a 911 call in the case, the boy's father said he and his 14-year-old son were at the school when a man followed the boy into the gym bathroom and molested him.

"I need me a cop before I kill somebody," the caller told a dispatcher.

The boy, police said, is not a student at Cary Academy. Headmaster Mitch McGuigan said the suspect was a contract employee of a company that cleans the school.

"He’s got to be gone," the caller in the 911 call said. "Security said he left all his cleaning stuff and left."

Police first informed the public of the crime on Monday, saying they had issued a warrant for an arrest. But they declined to talk about a suspect, fearing he would flee.

Now, police said they are asking for help from residents.

"After exhausting all investigative leads, the town of Cary is turning to citizens to help locate and arrest a man related to a sex incident with a minor," town officials said in a statement.

Lopez is charged with three counts of statutory sex offense, which carries a penalty of up to 16 years in jail.

Cary police said they have been working closely with the city of Raleigh’s Fugitive Task Force and are confident that Lopez is still in the area.

Anyone with information is asked to call Cary police at 919-469-4012 or Cary Crime Stoppers at 226-2746. Crime Stoppers pays up to $2,500 for information leading to an arrest or indictment, and callers can remain confidential.