An autopsy was to be performed to determine if the body was that of William McCune, 62, of Carson City, the Nevada Appeal reported.
Carson City Sheriff Ken Furlong said search-and-rescue teams found the body wrapped in what appeared to be a blanket in the river shortly after 8 a.m., the Carson City newspaper said.
KRNV-TV, Reno, reported co-workers called authorities when McCune didn't show up for work Thursday and investigators found blood in his apartments.
"The interior of the apartment looked as if there had been a pretty violent struggle," Furlong said.
The suspects were identified as Michael Paul Evans, 23, who was taken into custody in Carson City; and Anthony Elliot, 20, Makyla Blackmore, 20, and Raul Garcia, 22, who were arrested in Las Vegas, the TV station said.
The cause of death and a motive for the slaying were not reported.