Kenneth Fuller, 47, of West Goshen Township, was arrested Wednesday and charged with sexual assault, corruption of a minor and related offenses.
Fuller was a swimming coach at Bayard Rustin High School in West Chester. He has been fired since the allegations surfaced.
Prosecutors say Fuller had sex with the 17-year-old student, a member of the school's swim team, on three separate occasions between April 27 and May 2. The alleged assaults did not take place on school grounds.
Court documents allege Fuller had sex with the teen at Kennett Square Hotel on two occasions and the third encounter was at a park.
Prosecutors say on all three occasions, Fuller provided the student with alcohol. On one occasion, Fuller allegedly called the school pretending to be the victim's father, had the student excused from school for a doctor's appointment, then provided a fake doctor's note for the victim to take back to school.
Neighbors say Fuller is married and has three children and two of them are close in age to the alleged victim.
"I think everyone is still in shock and very devastated about what's happened," said Janice Christian.
"My thoughts are with his kids and wife and hopefully things get straightened out somehow," said James Fay.
Fuller seemed to have an ideal life. He owned a successful water treatment business which he operated out of his house, was a former All-American at Auburn and Olympic qualifier in swimming.
In addition to his coaching duties at Bayard Rustin, authorities say Fuller coached private lessons at Cheyney University, Pennypacker Country Club, Malvern and Wedgewood Swim Clubs.
Fuller's attorney, Francis C. Miller, said "The effect this is having on his team, the coaches, the school and his family is very upsetting to him."
Investigators are trying to determine if any other incidents occurred involving other students.
"We are actively looking and actively appealing for anyone else who may have information or any other victims to come forward," said D.A. Thomas Hogan.
They are asking anyone with information to contact Chester County Detective Matthew Gordon at 610-344-6866.