The Coast Guard earlier this month made public the ill-fated boat's certificate of inspection which prohibited it from being on the water when winds exceeded 35 mph and/or wave heights exceeded 2 feet.

The U.S. Coast Guard has referred the investigation into last month's deadly sinking of a Missouri tourist boat to federal prosecutors, officials said Tuesday.

Coast Guard spokeswoman Lisa Novak confirmed a report first published by the Kansas City Star that the case was referred to the U.S. attorney's office in Kansas City on Aug. 13. Don Ledford, spokesman for the U.S. attorney's office, said the Coast Guard referred the case "to consider a potential criminal investigation and federal prosecution." Both declined to discuss the matter further.

The accident occurred July 19 at Table Rock Lake near Branson. An amphibious duck boat sank amid strong winds, killing 16 passengers and one crew member. Fourteen people survived.

The Missouri attorney general's office also is conducting a criminal investigation that is looking into possible violations of the Missouri Merchandising Practices Act.

Ride the Ducks of Branson offers duck boat tours that begin in the southwestern Missouri town famous for its shows and entertainment, before the vessel enters the lake for an approximate 20-minute excursion. The attraction is owned by Ripley Entertainment.

Company spokeswoman Suzanne Smagala-Potts said Ripley is cooperating with investigators, including providing all documentation and materials requested.

"Meanwhile, our primary focus remains on doing everything we possibly can to ease the pain of the survivors, their families, and the families of the deceased," Smagala-Potts said in a statement. That includes paying funeral and medical expenses, she said.

The Coast Guard earlier this month made public the ill-fated boat's certificate of inspection which prohibited it from being on the water when winds exceeded 35 mph and/or wave heights exceeded 2 feet.

Video and audio from the boat, recovered by divers, showed that the lake was calm when the boat entered the lake. But weather suddenly turned violent and within minutes the boat sank.

The National Transportation Safety Board has said the wind speed at the time of the accident was more than 70 mph, just short of hurricane force. Weather forecasts had warned of an impending storm with winds possibly exceeding 60 mph.

The wave height wasn't known, but cellphone video shot by passengers on a nearby excursion boat showed waves that appeared to be far greater than 2 feet high.

Robert J. Mongeluzzi, whose Philadelphia-based law firm has filed lawsuits over the accident, said in a statement that those grieving the loss of loved ones "support holding fully accountable those responsible for making the deadly decisions that resulted in the catastrophe."

Margaret Stafford and Heather Hollingsworth in Kansas City, Missouri, contributed to this report.