Madeline Kingsbury’s parents are fighting to protect their grandkids from the children's father, who is being held on $1 million bond after he allegedly killed their daughter.

Adam Fravel, 29, was charged with two counts of second-degree murder for allegedly killing Kingsbury on March 31 and dumping her body in a taped-up, fitted bedsheet along a Minnesota highway, according to court documents. 

"It is fully anticipated that a new petition will be brought against Mr. Fravel to terminate his parental rights," Anna Tobia, the lawyer for Kingsbury's parents, wrote in Monday’s court filing during the custodial battle with Fravel. 

"Mr. Fravel is currently facing 40 years in prison if convicted of the charges. He poses a flight risk and based upon his actions when Winona County Health and Human Services first took custody of the children, there is every reason to believe he would flee with the children."

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madeline kingsbury

Minnesota mom Madeline Kingsbury disappeared on March 31 and was later found dead along a highway. (Madeline Kingsbury/Facebook)

Madeline’s parents — David and Cathy Kingsbury — referred to Fravel’s alleged April 4 standoff with the Winona social workers and police, who attempted to take custody of the 2- and 5-year-old children after Madeline, 26, went missing. 

"At one point, (Fravel) took the younger child into the residence and locked the door despite being told that the children were in the care and custody of Winona County," according to the petition filed by Winona County Health and Human Services, which was obtained by Fox News Digital.

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"While (Fravel) was in the home with the younger child, a social worker could hear (Fravel) shouting expletives."

When Fravel finally came outside, he allegedly argued with social workers while putting them in the wrong car seats and refusing to give social workers and police any of the kids’ belongings. 

Adam Fravel

Adam Fravel is charged with killing Madeline Kingsbury, the mother of his children. (Adam Fravel/Facebook)

Fravel didn’t have custodial rights when Kingsbury vanished and has been fighting his ex-girlfriend’s parents in court. 

As it stands now, the children are in the care of Kingsbury’s parents, but Fravel has supervised visitation rights at a secured location, and that's how his lawyers want things to remain. 

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Thomas Braun, who's representing Fravel in the custodial battle, said the Kingsburys' motion was "moot" and "misplaced" at a time when Fravel is behind bars, according to Tuesday's response letter to the judge.

"Opposing counsel’s attempts to try the facts related to the criminal proceeding in this CHiPS (Child in Need of Help or Protection) matter are misplaced," Braun wrote. "There continues to be no need for the county to litigate this matter given the temporary arrangements which have been put in place. Accordingly, Mr. Fravel objects to any modification of the current Court Order."

Madeline Kingsbury

Megan Kingsbury and her brother after learning about Madeline's "suspicious disappearance." (Megan Kingsbury)

Monday’s court filing, which was obtained by Fox News Digital, is the first motion in the custody bout since Fravel was formally charged with Kingsbury's murder. 

"Mr. Fravel has been hostile towards law enforcement, including making lewd comments, exposing himself and actively attempting to redirect their attention while they searched for Madeline Kingsbury," the lawyer for Kingsbury’s family wrote in the filing. 

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READ KINGSBURYS' FULL MOTION

"He is suspected to be the one who ripped these children’s mother away, forcing them to live a life without her presence. It is absolutely not appropriate nor in the children’s best interests for Mr. Fravel to have any access to them, even supervised."

Any interaction between Fravel and the children puts them at risk, the Kingsburys' lawyer argued. 

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Fravel and Kingsbury had an on-and-off-again relationship that included several instances of alleged physical abuse, according to the criminal complaint obtained by Fox News Digital. 

Kingsbury was missing for 69 days until a detective found her body on Highway 43 near the Iowa state line with a knotted towel wrapped around her neck, the criminal complaint says. 

Adam Freval

Adam Fravel (Winona County Detention Center)

Kingsbury worked as a research coordinator at the Mayo Clinic and electronically sent Fravel money to pay household bills, the complaint says. Fravel had been working as a software engineer.

She then "suspiciously" and "involuntarily" disappeared on March 31, according to the police, at a time when the couple was in the process of splitting up and Fravel was moving out of the house, according to the complaint.

FATHER OF MISSING MINNESOTA WOMAN'S CHILDREN BREAKS SILENCE 12 DAYS AFTER SHE VANISHED

Fravel released one public statement through his lawyer during the 69-day search for Kingsbury. 

On day 12 of her disappearance, Fravel said he "did not have anything to do with Maddi's disappearance," and that he and his family were "subject to a myriad of accusations regarding (Maddi's) disappearance."

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The Kingsbury family said in a statement after Fravel’s arrest last Wednesday that "the right person is in custody."

"We’re glad he’s in custody," her sister, Megan, said. "He’s not walking around a free man anymore."