OKMULGEE, Okla. (KFOR) – Authorities are releasing new details in the mysterious disappearance of four men in Okmulgee.

One week ago, family members reported 32-year-old Mark Chastain, 30-year-old Billy Chastain, 32-year-old Mike Sparks, and 29-year-old Alex Stevens missing.

On Monday afternoon, Okmulgee authorities announced that the remains have been positively identified as the missing men.

“This investigation is now a murder investigation,” said Okmulgee Police Chief Joe Prentice.

Chief Prentice said all four men suffered gunshot wounds and were dismembered before their remains were thrown in the river.

“That is what caused difficulty in determining identity,” he said, adding that the river appears to have been used as a dump site.

The Okmulgee Police Department says all four are close friends and are believed to have left Billy Chastain’s house on the west side of Okmulgee on Oct. 9.

All were reportedly on bicycles.

Throughout the investigation, authorities have received multiple reports of sightings of the men. However, they were not able to confirm any of those sightings.

On Friday afternoon, search crews stumbled upon human remains in a river southwest of Okmulgee.

Prentice says they are still trying to determine a timeline for the murders, but said that the bodies were probably disposed of early Monday morning.

Before the group went missing, Prentice says he believes that the men were planning to commit a crime, according to a statement from a witness.

“We do not know what they planned or where they planned to do it,” he said.

Investigators say they searched a salvage yard where one of the men’s phones was tracked, but they didn’t find anything at the salvage yard. However, Prentice says evidence of a ‘violent event’ was found at a nearby property.

Now, the owner of the salvage yard, Joe Kennedy, is considered a person of interest in the case, but has not been officially named as a suspect. Officials say Kennedy is now missing.

According to Okmulgee Police Department, Joe Kennedy’s blue PT Cruiser has been located and is in police custody.

They say it was abandoned behind a business in Morris, Oklahoma. Investigators are looking into how it came to be there.

Prentice says during previous interviews, Kennedy has denied knowing the men.

Police say they are also still searching for the missing bicycles.

“I’ve worked over 80 murders in my career. I have worked murders involving multiple victims. I have worked dismemberments. But this case involves the highest number of victims and it’s a very violent event,” said Prentice. “So I can’t say that I’ve never worked anything like it, but it’s right up there at the top.”

Anyone with any information about the murders, or Kennedy’s location, is asked to call (918) 756-3511.