The U-S Coast Guard is holding an investigative hearing in Sioux City tomorrow on the death of a woman aboard the Sioux City Belle. 59-year old Pat Thompson of Sioux City died on the casino riverboat last Friday. Thompson was apparently hit in the head with an object during a lifeboat safety drill. Lieutenant Joe Rock is leading the investigation for the Coast Guard.Rock says they want to determine exactly what happened and who is responsible. He says the hearing will also determine if there was any violation of the law. Rock says this type of accident is very rare.He isn’t sure when the Coast Guard will issue its final report on the accident.Casino general manager John Pavone says the Coast Guard investigation is one of three being performed. He says the casino and the Iowa Department of Criminal Investigation are each conducting and investigation.Pavone was not on the boat at the time, but arrived soon after he was informed about the accident. He says it’s a tragic thing that was a “freak accident.” He says they want to get to the bottom of the issue so it never happens again. Pavone says right now there is only speculation about the cause.The Coast Guard hearing begins tomorrow morning at the federal courthouse in Sioux City.