Amy Duggar King says her "heart plummeted" after Joseph Duggar’s arrest. She's the author of "Holy Disruptor: Shattering the Shiny Facade by Getting Louder with the Truth."

Joseph Duggar may face one of the most damaging forms of evidence in court — his own admission — after investigators said he acknowledged impure intentions in discussions about alleged contact with a minor.

Duggar is set to appear in court Monday in the ongoing criminal case against him.

A Florida affidavit, obtained by Fox News Digital, revealed that the case against the former reality TV star may hinge not just on a victim’s account, but on his own words. According to investigators, Duggar admitted to inappropriate contact with a minor during both a confrontation with the victim’s father and a subsequent recorded call coordinated with law enforcement, acknowledging his "intentions were not pure."

Former federal prosecutor Neama Rahmani emphasized the admission could be "highly relevant and damaging" to any defense put forth by Duggar's team.

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Joseph Duggar pleaded not guilty to child molestation charges and demanded a jury trial during a court appearance on March 31. (Courtesy: Bay County Court)

"It is evidence of intent, the victim, and the timing of the alleged abuse," Rahmani told Fox News Digital. "His lawyers will try to argue that it is too vague and attenuated and try to get it excluded on that basis. I don't think they will be successful because the statement was made in the context of Duggar also admitting to inappropriate touching under a blanket. A judge is unlikely to separate the two statements, and this is why pretext calls like this can be so powerful if they lead to incriminating evidence."

Duggar, who starred with his parents and siblings in TLC's "19 Kids and Counting," was arrested on March 18 in Arkansas. His arrest came after authorities interviewed a 14-year-old girl who claimed Duggar had inappropriately touched her several times on a family vacation when she was nine years old.

Florida Judge Brantley Clark ordered the reality TV star held on $600,000 bond after he pleaded not guilty during his first appearance in Bay County Court on March 31. He posted bail later that day.

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Joseph Duggar also faces unrelated charges in Arkansas. (Washington County Sheriff's Office/AP)

The affidavit filed in Bay County outlined more specific allegations about the interactions during that 2020 trip.

"During the vacation, the defendant asked the victim to sit on his lap, numerous times," the document read. "The victim would sit on the defendant’s lap. The defendant would cradle the victim with his arms. As the vacation continued, the defendant would ask the victim to sit on the couch beside the defendant. The defendant covered the parties with a blanket."

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According to the investigation, the alleged victim, who was nine-years-old at the time, claimed Duggar inappropriately touched her genitals and her thighs.

"The victim stated the defendant’s hand was outside of her underwear when these incidents occurred," the affidavit said. "The victim stated this made her feel uncomfortable and confused. The victim stated the defendant eventually approached the victim and apologized for his actions. The incidents stopped occurring after the defendant apologized for his actions."

John David, Josiah and Joseph Duggar are interviewed for "Good Morning America" in 2016. (Ida Mae Astute/Disney General Entertainment Content via Getty Images)

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Legal experts explained Duggar's own words in the affidavit could become a key point of contention as the case moves forward.

"‘My intentions were not pure’ is the kind of statement prosecutors love because they can frame it as a confession without the defendant ever fully confessing," criminal defense attorney Duncan Levin told Fox News Digital. "It gives them language they can put in front of a jury and say, in effect, he told you himself. But from a defense standpoint, that phrase is still frustratingly vague."

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"It is not a clear admission to a criminal act," Levin, who previously defended Harvey Weinstein, added. "It could reflect shame, sinful thoughts, or inappropriate intent, but criminal cases are supposed to turn on proof of conduct, not ambiguous language. The defense strategy would be to argue that prosecutors are trying to turn a morally charged but indefinite statement into something far more specific than it actually is, and to insist that the state prove the charged conduct with concrete evidence rather than asking jurors to fill in the gaps."

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Joseph Duggar with his wife, Kendra.  (Duggar Family/Instagram)

While the admission of impure intentions when it comes to a minor child might convict Duggar in the court of public opinion, one legal expert noted there's a different standard when it comes to the courtroom.

"The public hears language like this and frequently forms conclusions about guilt before any evidence is presented," Tom Maronick told Fox News Digital. "However, a jury is held to a different standard. The legal system operates on facts, statutory elements, and provable evidence, not public sentiment or emotional interpretation."

"A single ambiguous statement, unsupported by corroborating criminal conduct, represents a significant gap between accusation and conviction," the criminal law attorney said. "That distinction is essential in criminal defense."

The Duggars became famous after the premiere of their reality TV show, "19 Kids and Counting." (Ida Mae Astute/Disney General Entertainment Content via Getty Images)

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Duggar's defense strategy will likely focus on two things: the context in which the statement was made and how it was obtained, according to Maronick. The lawyer noted the statement could be suppressed in court if it was obtained through leading questions, a prolonged interrogation, or coercive tactics.

"Beyond that, the core argument is straightforward, saying something is fundamentally different from doing something," Maronick explained. "Intent language without proof of actual criminal conduct falls short of what is required for conviction."

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