A teenager charged with killing four students at their Michigan high school waived a key hearing Friday, moving his case straight to a trial court, while a judge rejected a request by his parents to reduce their $500,000 bail and get them out of jail.

Prosecutors vigorously opposed a lower bond for James and Jennifer Crumbley, who are charged with involuntary manslaughter in the deaths at Oxford High School. They countered with more examples of the parents' alleged failure to get help for Ethan Crumbley before the Nov. 30 shooting.

This undated combo of photos provided by the Oakland County Sheriff's Office shows James Crumbley, left, and Jennifer Crumbley, the parents of Ethan Crumbley, a teen accused of killing four students in a shooting at Oxford High School, in Michigan.(Oakland County Sheriff's Office via AP, File)

This booking photo released by the Oakland County, Mich., Sheriff's Office shows Ethan Crumbley, who is charged as an adult with murder and terrorism for a shooting that killed four fellow students and injured more at Oxford High School in Oxford, Mich. (Oakland County Sheriff's Office via AP, File)

"He was fascinated with firearms. He was violent. He displayed terrifying tendencies and behaviors," assistant prosecutor Marc Keast said. "He literally sketched out what he planned to do in his journal and his drawings."

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Earlier in 2021, Ethan told his mother in text messages that he thought "there was a demon or a ghost or someone else inside the home," Keast said. "These weren't one-time messages. He would repeatedly text what he was perceiving to his mother, who sometimes would not respond for hours."

The elder Crumbleys are accused of making a gun accessible to their son and refusing to take him home on the day of the shooting when school counselors confronted them with distressing drawings of violence.

Judge Julie Nicholson declined to reduce the parents' bond to $100,000, noting they didn't turn themselves in after charges against them were announced on Dec. 3.

This image from 52-3 District Court shows Ethan Crumbley in a Zoom hearing in Rochester Hills, Mich., Friday, Jan. 7, 2022. (AP Photo/Carlos Osorio)

This image from 52-3 District Court shows James and Jennifer Crumbley in a Zoom hearing in Rochester Hills, Mich., Friday, Jan. 7, 2022. (AP Photo/Carlos Osorio)

This image from 52-3 District Court shows Jennifer Crumbley waving to her husband James during a Zoom hearing in Rochester Hills, Mich., Friday, Jan. 7, 2022. (AP Photo/Carlos Osorio)

Separately, Ethan Crumbley, 15, is charged as an adult with murder and other crimes. Earlier Friday, he waived a key evidentiary hearing and agreed to send his case directly to a trial court in Oakland County.

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After the brief hearing, defense attorney Paulette Loftin told WWJ-AM that a plea deal down the road was a "definite possibility," though "it's too early to jump to that phase."

Lawyers for the parents said they weren't trying to flee in early December, though they had $6,000 in cash and multiple phones and credit cards when they were arrested in a Detroit art studio.

This image from 52-3 District Court shows James and Jennifer Crumbley in a Zoom hearing in Rochester Hills, Mich., Friday, Jan. 7, 2022. (AP Photo/Carlos Osorio)

This image from 52-3 District Court shows Jennifer Crumbley signing a message to her husband James in a Zoom hearing in Rochester Hills, Mich., Friday, Jan. 7, 2022. (AP Photo/Carlos Osorio)

This image from 52-3 District Court shows Jennifer Crumbley in a Zoom hearing in Rochester Hills, Mich., Friday, Jan. 7, 2022. (AP Photo/Carlos Osorio)

"The last thing they expected was that a school shooting would take place, or that their son would be responsible," defense attorneys Shannon Smith and Mariell Lehman said in a court filing.

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Oxford High students are expected to return to school next week for the first time since the shooting but at a different building. The high school, roughly 30 miles (50 kilometers) north of Detroit, could reopen during the week of Jan. 23.