DISMEMBERED bodies found in the Deep Fork River in Oklahoma have been identified as those of four men reported missing last week, the local police chief said on Monday, adding: "This is now a murder investigation."

Investigators found the first remains on Friday and determined over the weekend that the victims died from gunshot wounds before they were cut up and dumped into the river, Okmulgee Police Chief Joe Prentice told a news conference.

"All four bodies were dismembered before being placed in the river and that is what caused the difficulty in determining identity," Prentice said. "The river appears to be a dump site. This is now a murder investigation."

The victims have been confirmed as Mark Chastain, 32, Billy Chastain, 30, Mike Sparks, 32, and Alex Stevens, 29, the police chief said. Mark and Billy Chastain are brothers.

The men were reported missing on Oct. 9 after leaving Billy Chastain's home in Okmulgee on bicycles around 8 p.m. Okmulgee is a city of roughly 11,000 people 40 miles (64 km) south of Tulsa.

Prentice said investigators believe the men intended to "commit some sort of criminal act" that night. A witness told police that the men invited him to join them and would "hit a lick big enough for all of them."

The owner of a Okmulgee salvage yard, Joe Kennedy, is considered a person of interest in the case after "evidence of a violent event" was discovered on an adjacent property, Prentice said. Police were led to that area by a ping from Mark Chastain's phone.

Kennedy had not been named a suspect in the case but was missing and possibly suicidal, the chief said, asking the public to report any sightings of him.

The North Fork River is a tributary of the North Canadian River that flows through Okmulgee on its way to Lake Eufala.