A witness told police that Montes admitted he was present when Kenyatta was killed and had assisted in getting rid of the body by dumping it, charging documents show. Blood spatter was later found inside the Nitro, authorities allege.
Police have already arrested Frank Paul Reyos, 30, on suspicion of homicide, and his sister, Jessica Reyos, 38, and Frank Reyos' girlfriend, Brittney Montano, 21, on suspicion of helping cover up Kenyatta's death.
Police also questioned Stephon Evans, 21, Camille Lopez, 20 and Natasha Alvarado, 33, after publicly announcing investigators were seeking their whereabouts. Police also announced they were questioning Shelby Reed, 19, in connection with the death, though no warrant had been issued for her arrest.
Attorney Tyler Williams, who has been hired to represent Reed, said homicide detectives were not providing incentive for anyone to cooperate.
"Next thing I know, they're arresting Jessica and her family for obstruction of justice," Williams said. "They're trying to strong-arm these people. They're just trying to bully these people into making some sort of statement."
Salt Lake City police said they had no comment on the allegations.
Kenyatta's body was discovered Aug. 29 dumped in a vacant Sugar House lot near 1120 E. Crandall Ave. (about 2900 South). Police have not released a motive in the slaying.
Williams said police want to speak with Reed because police believe she was one of the last people to speak with Kenyatta.
He said Kenyatta, who had been acquainted with the Reyos family for a few weeks, had called Reed Aug. 26 the day he was last seen alive asking for a ride, but Reed had told him she couldn't go out.
"She has no idea about what happened," Williams said. "If somebody with the family is responsible, I think Jessica and Shelby, they want to help. They want to say what they know. Just right now, they don't know anything."
As of Thursday afternoon, no charges have been filed against anyone other than Montes.
Frank Reyos and Alvarado have been returned to state prison on unrelated parole violations. Montano remained in the Salt Lake County jail. After spending 72 hours behind bars without being charged, Jessica Reyos was released on her own recognizance, Williams said.
Evans and Lopez were questioned and released, police said Thursday.
Williams said Reed has cooperated with police and already provided them a statement. And when she expressed a willingness to come in and talk again, detectives told Williams they planned to arrest her for obstructing justice, even though they don't have a warrant.
"There's no reason for her to make these statements when they're just going to throw her in jail," he said.
Salt Lake County District Attorney Sim Gill said he cannot comment on pending investigations and noted that only one criminal case had been filed so far.
"We screen cases as they're presented to us," he said.