Two young women told authorities they helped burn a 17-year-old boy's body after a man gouged out the teen's eyes, repeatedly stabbed him and bragged about the killing in southern Missouri, according to newly released court records.

The details were included in case documents filed after the arrests of Andrew Vrba and Isis Schauer, who are both 18, and 24-year-old Briana Calderas. The three were charged Thursday with first-degree murder and abandonment of a corpse in the death of Joseph Steinfeld.

Court documents allege Facebook messages were found on Schauer's phone from an account linked to Vrba, telling her to "stick to the story" and "quit talking." Vrba later told investigators he killed Steinfeld, though he didn't provide a motive, according to case documents.

The three suspects are being held without bond. Vrba's attorney declined comment to The Associated Press on Friday, while no attorneys were listed in online court records for Schauer or Calderas.

Steinfeld's burned remains were found this week near Calderas' mobile home in Cabool, a rural area about 70 miles (113 kilometers) east of Springfield. His family reported him missing on Sept. 14, saying no one had seen him for a couple weeks.

The last people with Steinfeld were the three suspects, whom the family had spoken to and believed to be lying about the teen's whereabouts, according to a probable cause statement from a sheriff's deputy in Missouri's Texas County.

When questioned Wednesday, Schauer denied any knowledge of Steinfeld's whereabouts. She said the teen was last seen leaving a Cabool home after having a physical altercation with Vrba. But after obtaining permission to look at her phone, a sheriff's deputy saw the Facebook messages.

Schauer told the deputy she couldn't remember what the conversation was about, but later admitted she was aware of the killing and helped get rid of the body, the probable cause statement said.

Vrba told investigators he had to kill Steinfeld, and initially tried to poison him, though the probable cause statement didn't provide a possible motive for the attack. The detective wrote that Vrba then described how he stabbed Steinfeld in the living room of the home.

Vrba said the trio burned Steinfeld's body, and placed some of the bones into a garbage bag and that the bag was placed in a chicken coop near the residence. The women said Vrba told them he had gouged Steinfeld's eyes and stabbed him in his genitals, and bragged about the killing, the detective wrote.

The detective said Calderas admitted Steinfeld was killed at her home and that she helped burn the body, but that she didn't want him dead. Schauer and Vrba disagreed, saying that Calderas mentioned several days earlier that she wanted Steinfeld to die. Calderas led authorities to the knife used in the killing and Steinfeld's phone, the detective wrote.

Vrba and Schauer also are charged with armed criminal action. The pair and Steinfeld are from Houston, Missouri, about 20 miles (32 kilometers) northeast of where the body was found.