A Michigan judge on Saturday set a combined $1 million bond for the release of the parents of a 15-year-old teen who is charged with killing four students at a U.S. high school with a gun bought by his father. The parents pleaded not guilty to involuntary manslaughter while new details about the lead-up to the deadly day revealed several red flags that most believe should have pushed the school and parents to take action before the shooting.

James and Jennifer Crumbley entered not guilty pleas to each of the four involuntary manslaughter counts against them during a hearing held on Zoom. Jennifer Crumbley sobbed and struggled to respond to the judge's questions at times and James Crumbley shook his head when a prosecutor said their son had full access to the gun used in the killings.

Judge Julie Nicholson assigned bond of $500,000 apiece to each of the parents and required GPS monitoring if they pay to be released, agreeing with prosecutors that they posed a flight risk.

Defense attorneys for the Crumbleys still argued Saturday that they never intended to flee and had made plans to meet their lawyers early that morning. Attorney Shannon Smith accused prosecutors of "cherry picking" facts to release publicly, including the accusation that their teenage son had unrestricted access to the handgun prosecutors say his father purchased for him days before the shooting.

"Our clients are just as devastated as everyone else," Smith said, adding that the gun "was locked." She didn't provide more detail during Saturday's hearing.

Oakland County Prosecutor Karen McDonald’s office filed involuntary manslaughter charges against the Crumbleys on Friday, accusing them of failing to intervene on the day of the tragedy despite being confronted with a drawing and chilling message – "blood everywhere" – that was found at the boy’s desk.

The Crumbleys committed "egregious" acts, from buying a gun on Black Friday and making it available to Ethan Crumbley to resisting his removal from school when they were summoned a few hours before the shooting, McDonald said Friday.

Authorities had been looking for the couple since Friday afternoon. Late Friday, U.S. Marshals announced a reward of up to $10,000 each for information leading to their arrests.

Smith, the Crumbleys’ attorney, had said Friday that the pair left town earlier in the week "for their own safety" and would be returning to Oxford to face charges.

During Saturday's hearing, Smith said they were in touch by phone and text on Friday evening and blamed prosecutors for failing to communicate with her and fellow defense attorney Mariell Lehman.

"Our clients were absolutely going to turn themselves in; it was just a matter of logistics," she said.

But McDonald said on Saturday that the couple took $4,000 out of an ATM on Friday morning in Rochester Hills, not far from the courthouse where they should have appeared that afternoon.

"These are not people that we can be assured will return to court on their own," she said.

A Detroit business owner spotted a car tied to the Crumbleys in his parking lot late Friday, Oakland County Undersheriff Michael McCabe said in a statement. A woman seen near the vehicle ran away when the business owner called 911, McCabe said. The couple was later located and arrested by Detroit police.

Detroit Police Chief James E. White said the couple "were aided in getting into the building," and that a person who helped them may also face charges.

On Friday, McDonald offered the most precise account so far of the events that led to the shooting at Oxford High School, roughly 50 kilometers (30 miles) north of Detroit.

Ethan Crumbley, 15, emerged from a bathroom with a gun, shooting students in the hallway, investigators said. He’s charged as an adult with murder, terrorism and other crimes.

Under Michigan law, the involuntary manslaughter charge filed against the parents can be pursued if authorities believe someone contributed to a situation where there was a high chance of harm or death.

Parents in the U.S. are rarely charged in school shootings involving their children, even as most minors get guns from a parent or relative’s house, according to experts.

School officials became concerned about the younger Crumbley on Monday, a day before the shooting, when a teacher saw him searching for ammunition on his phone, McDonald said.

Jennifer Crumbley was contacted and subsequently told her son in a text message: "Lol. I’m not mad at you. You have to learn not to get caught," according to the prosecutor.

On Tuesday, a teacher found a note on Ethan’s desk and took a photo. It was a drawing of a gun pointing at the words, "The thoughts won’t stop. Help me," McDonald said.

There also was a drawing of a bullet, she said, with words above it: "Blood everywhere."

Between the gun and the bullet was a person who appeared to have been shot twice and is bleeding. He also wrote, "My life is useless" and "The world is dead," according to the prosecutor.

The school quickly had a meeting with Ethan and his parents, who were told to get him into counseling within 48 hours, McDonald said.

The Crumbleys failed to ask their son about the gun or check his backpack and "resisted the idea of their son leaving the school at that time," McDonald said.

Instead, the teen returned to class and the shooting subsequently occurred.

"The notion that a parent could read those words and also know that their son had access to a deadly weapon that they gave him is unconscionable – it’s criminal," the prosecutor said.

Jennifer Crumbley texted her son after the shooting, saying, "Ethan, don’t do it," McDonald said.

James Crumbley called 911 to say that a gun was missing from their home and that Ethan might be the shooter. The gun had been kept in an unlocked drawer in the parents’ bedroom, McDonald said.

Ethan accompanied his father for the gun purchase on Nov. 26 and posted photos of the firearm on social media, saying, "Just got my new beauty today," McDonald said.

Over the long Thanksgiving weekend, Jennifer Crumbley wrote on social media that it is a "mom and son day testing out his new Christmas present," the prosecutor said.

Asked at a news conference if the father could be charged for purchasing the gun for the son, McDonald said that would be the decision of federal authorities.

In a video message to the community Thursday, the head of Oxford Community Schools said the high school looks like a "war zone" and won’t be ready for weeks. Superintendent Tim Throne repeatedly complimented students and staff for how they responded to the violence.

He also acknowledged the meeting of Crumbley, the parents and school officials. Throne offered no details but summed it up by saying, "No discipline was warranted."

McDonald was asked about the decision to keep Crumbley in school.

"Of course, he shouldn’t have gone back to that classroom. ... I believe that is a universal position. I’m not going to chastise or attack, but yeah," she said.

Asked if school officials may potentially be charged, McDonald said: "The investigation’s ongoing."