Hughes could face a minimum of 10 years in prison if convicted of the sodomy charge alone, Byrne said.
Hughes had just finished a three-day training seminar and was staying at a nearby Sheraton hotel, but he and a colleague decided to stay another night at the Ritz-Carlton, Byrne said.
Hughes stayed out later than his coworker, and when he returned to the hotel, he tried to get into a room on the sixth floor, where he had been staying at the Sheraton. But his room at the Ritz-Carlton was on the eighth floor, Byrne said.
Hughes asked for a new key at the front desk, and the clerk issued him one without checking whether the room number was correct, police said.
The two-room suite was occupied by a St. Louis family, and Hughes entered the room where three girls slept: the 9-year-old, her 14-year-old sister, and another 14-year-old, police said.
Hughes unlocked the door, kicked the door open when the chain lock caught, and crawled into bed with the 9-year-old, Byrne said. The other girls did not wake up while Hughes allegedly assaulted the youngest girl.
The 9-year-old eventually alerted her parents, who called police about 4:40 a.m.
"He was captured in the lobby in just his underwear," Byrne said.
Hughes has been suspended from his job at Enterprise, said Christy Conrad, a company spokeswoman.
The St. Louis Post-Dispatch reported that the hotel clerk who gave Hughes the key had resigned, but a hotel spokesman declined to confirm this Tuesday, citing privacy policies in personnel matters.
Contact staff writer Joelle Farrell at 610-627-0352 or at jfarrell@phillynews.com.