Relatives say that Alvin Troub, 20, probably tried to rescue Michael Runyon, 8, after the younger boy fell in the water, The Portland Oregonian reported. Michael did not know how to swim.
"Alvin would have been in the water in a heartbeat," said Laurie Runyon, their aunt.
On Sunday, Archie Vibbard, their grandfather, dropped the brothers off at Riverview Park in Independence, Ore. When he returned, he could not find them but their bait boxes and fishing poles were on the dock.
Police teams and volunteers, with tracker dogs, combed the river's banks until Tuesday afternoon. In early afternoon, first Troub's body and then his brother's were found in 10 feet to 15 feet of water near a spot pinpointed by a dog team.
Deb Walker, who joined the search with her German Shepherd, Mickey, said that the effort was complicated by high water and a strong current.
Swim Week Miami Beach 2014 [PHOTOS]