Schwyz canton police spokesman Florian Grossmann said that Hingis, her mother Melanie Molitor and her mother's boyfriend Mario Widmer were interviewed at its headquarters last week.
Grossmann added that the canton justice department will decide possible further action.
French equestrian athlete Thibault Hutin said he was attacked on Sept 23 at his home in Feusisberg. He claimed that Hingis and Molitor hit him, and Widmer struck him with a DVD player.
33-year-old Hingis came out of retirement this year to play doubles with Daniela Hantuchova at US Open tournament.