"We're not certain, but it appears Mr. Schantz may have fallen into the river," said Riley. "At no point was he ever approached or accompanied by any individual."
Michael Schantz said that he and his two younger siblings and their mom are bracing for bad news.
"He wasn't only a father to us, he was also a best friend and a role model," he said. "My brother has some special needs and doesn't have that many friends and my dad was always just so patient and loves him to death."
Schantz's wife, Lori, is not doing well, said the son.
"He was the love of her life. They've been married 29 years and first met when they were teenagers," he said.
"But we're hoping for the best, and preparing for the worst."
ABC News' Ryan Owens contributed to this report.