Photo: Okmulgee Police Department (4)

Top row L-R: Billy Chastain, Mark Chastain Bottom Row L-R: Alex Stevens, Mike Sparks

Police have shared gruesome details about the fate of four friends from Oklahoma who went missing after riding off together on their bikes.

Their official cause of death hasn’t been confirmed but they were shot, Prentice said.

“All four bodies were dismembered before being placed in the river, and that is what caused difficulty in determining identity,” he added. “The river appears to be a dump site.”

Now, the missing persons investigation is considered a murder investigation.

Prentice said authorities haven’t confirmed what the men planned to do or where.

Kennedy was then reported missing on Saturday “and may be suicidal,” said Prentice.

He was driving a blue Chrysler PT cruiser with Oklahoma plates. Because he’s not a suspect, Prentice said he doesn’t plan on issuing his photo to the public. He later said he doesn’t believe Kennedy is a threat but urged anyone who sees him to contact authorities.

“We have worked around the clock all week, we were out all weekend and we will continue to work to figure out what exactly happened to their loved ones and who did it,” Prentice said.

He added that investigators have not found the men’s bicycles.

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

He later said that Kennedy had been cooperating with police before he went missing, and said he didn’t know the victims.

Their families were “distraught” and “shocked” when told of the developments in the investigation.

“It was abandoned behind a business in Morris, Oklahoma. Investigators are looking into how it came to be there. Currently, we have no vehicle information for Kennedy,” thebrief statementreads via Facebook.

The Okmulgee Police Department tells PEOPLE it has nothing further to add at this time.

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“All four are close friends and are believed to have left Billy Chastain’s home on the west side of Okmulgee on Sunday at around 8 PM,” the department said in a statement on social media. “All were reportedly on bicycles. Two of the men are believed to have cell phones with them, but attempts to call go straight to voicemail.”

source: people.com