LAKE OF THE OZARKS, Mo. -

A Clive, Iowa man drowned at the Lake of the Ozarks Saturday after falling overboard.

According to Missouri State Highway Patrol reports, 20-year-old Brandon Ellingson was being transported for a boating while intoxicated arrest around 5:23 p.m.

Troopers said he then walked to the starboard side of the boat and either fell or jumped overboard.

Sergeant Paul Reinsch of the Missouri State Highway Patrol said Ellingson, who was handcuffed and wearing life vest, was sitting to the left of the trooper driving the boat. Ellingson then stood up, took a few steps back and made it to the opposite side of the boat.

"After the subject fell into the lake, the trooper first tried to retrieve him, and then actually go into the water to rescue him, and wasn't able to do so," Reinsch said.

At some point, Ellingson's life vest came off. Reinsch wasn't sure if it came off immediately after Ellingson fell into the lake.

Jim Bascue was driving a water taxi when he saw the Patrol's boat stopped, trying to rescue Ellingson. Bascue said he tried to help, as well, throwing a rescue buoy to Ellingson. After a while, Bascue said Ellingson's life vest came off. That's when the trooper jumped into the water in an attempt to save him.

"Obviously a very serious situation," Reinsch said. "We're looking into how the victim got out of his seat, went over to the side of the boat and then either jumped or fell off the boat."

The Patrol Dive Team recovered his body hours later, at 11:26 a.m. Sunday. Ellingson had been missing in about 80 feet of water in the Gravois Arm at the 3.5 mile marker of the main channel.

Ellingson's death was the second drowning at the Lake of the Ozarks in two days. A Columbia man never resurfaced after jumping in to help a friend who fell overboard late Friday night.

The Associated Pres reported Ellingson was currently attending Arizona State University.

According to the school's online directory, he was enrolled as a business student.

The Sigma Chai Fraternity's Arizona-based chapter said on its Facebook page Sunday that Ellingson had been a member since 2012 and asked for prayers for his family.

(Author's note: This story has been edited to add information from witnesses.)