The search started late Saturday night, October 24, 2015. A white man in his 50s fell off of a boat into the Mississippi River.
Illinois DNR officials say it was a large recreational boat with two levels.
"People aren't always in visible sight. It's not like having a small boat where if someone falls out you're going to know it," says Sergeant Anthony Petreikis.
And this made the search even more challenging because no one saw where the man fell in.
"This one is a lot more difficult just because the distance we have to cover in the searches is much greater," says Petreikis.
The Saturday night search had to be called off after just two hours because of darkness. But it picked back up Sunday morning, and it stretched all the way from Sunset park in Rock Island past the I-280 bridge into Buffalo, Iowa.
Today the US Coast Guard, Illinois and Iowa DNR and the Rock Island Fire Department searched the water's surface and used sonar technology to look underneath. These efforts fell short. But the search will continue throughout the week.