Story highlights Man is accused of sexually abusing another passenger on flight to Detroit

Woman claims she was asleep

(CNN) Investigators arrested a man they say unbuttoned the shirt and pants of a sleeping female passenger and put his hand down her pants during a flight, according to a criminal complaint filed in federal court.

Prabhu Ramamoorthy faces a charge of aggravated sexual abuse after a 22-year-old woman accused him of assaulting her on a Spirit Airlines flight from Las Vegas to Detroit on Wednesday morning.

The case is just one alleged example of what some women have said is a hidden reality of commercial air travel . Though it's difficult to track how frequently assaults occur on flights, FBI investigations into midair sexual assaults have increased by 66% from fiscal year 2014 to 2017.

The federal public defender's office declined to comment on the Ramamoorthy case. Richard O'Neill, Ramamoorthy's appointed attorney, did not immediately respond to CNN's request for comment.

A detention hearing was held Thursday. According to the Detroit News, O'Neill said, "I have a hard time with some of these allegations but that's what a trial is for. There have been no allegations from anywhere that his behavior has ever been inappropriate prior to this incident."

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