One of the keys to to the conviction of Byron Case in State v. Case was an audiotaped conversation between Case (when he was still only the Prime Suspect) and Kelly Moffett (known before the arrest as "Cooperating Witness"). Case and many of his supporters believe that this represented a miscarriage of justice.

The specific incident in question is as follows:

The Cooperating Witness telephoned the Prime Suspect late on the night of June 5, 2001 at the behest of the Jackson County Sheriff's Department, attempting to engage him in conversation about the murder with the story that she had again been contacted by investigators, and that she could no longer remember the alibi to which they had agreed. The conversation had progressed for more than three minutes, with the main subject being what she should say to investigators, when she made the direct reference to him having committed the murder:¹

CW = "Cooperating Witness" PS = "Primary Suspect"

    (3:15)
      CW:  [The police] called me while I was in rehab, they showed up out there. Yeah, I don’t understand, 
           like seriously, what all went on or whatever, and I seriously, I hate to say this, but why, 
           seriously, why did you have to kill her? What was the whole fucking big deal? Could you 
           explain that to me?
    (3:30)
      PS:  [no response]
      CW:  Because I don’t get it. Seriously. Justin’s dead for no reason, [Anastasia’s] dead for no reason, 
           it’s all just fucked up. And for some reason they’re talking to me, because you won’t talk. So 
           I’m fucked. And it makes me look horrible because everybody already knows that I’m a fucking 
           crack-head, and that I’m a coke-head, that I’m an alcoholic so I don’t remember shit. And if I 
           tried to talk to them, nothing’s going to add up.
      PS:  [no response]
    (4:00)
      CW:  So, I mean, if you could, seriously, explain to me as to why you actually felt the need to 
                kill her, than that would really help me feel better about the whole fucking thing.
      PS:  [no response]
      CW:  I mean, was there, seriously, any reason to all of this?
      PS:  We shouldn’t talk about this.
      CW:  Why?
    (4:20)
      PS:  Probably because we shouldn’t talk about this.

According to Black's Law Dictionary, a tacit (or implied) admission is "an admission reasonably inferable from a party's action or statement, or a party's failure to act or speak." It means that a jury can reasonably take a defendant's failure to deny a direct accusation to be an admission in itself.

In this conversation, in which both Case and Moffett discussed the ongoing police investigation into Anastasia's murder, and specifically Moffett's claim that police were wanting to question her again about it, Case talked with her quite straightforwardly and coherently, and gave her direct advice on dealing with police questions. However, when she made three clear and direct accusations that Case was himself Anastasia's killer, Case suddenly became evasive, choosing not to respond to her questions, and then deliberately steering her away from the subject by saying "We shoudn't talk about this". The trial jury was allowed, but not required to consider Case's silence when directly accused of murder to be a tacit admission. Having the choice, the jury considered the defendant's silence and evasion of the question to be tantamount to an admission of guilt.

One of the arguments made by many of Byron Case's supporters since his conviction is that anyone could have accosted anyone else, accused them of killing anyone, and that a failure to challenge that accusation could be effectively used as evidence against them. In doing this they exaggerate the concept of tacit admission and completely ignore the fact that Case was directly accused of committing the murder in a converstation in which he had been talking about the murder investigation. The accusation had not come out of the blue. He had not been suddenly blindsided by the question. It was not the first time he had dealt with this accusation, directly or indirectly.

Given the nature of the conversation that preceded the accusations, a reasonable person would question why Case did not simply tell Moffett, "Don't be ridiculous. I didn't kill her," or say "I don't know what you're talking about", or even treat her condescendingly as if he thought her irrational, answering with a "yeah, sure". In fact, according to one juror, a reasonable person would wonder, when in the middle of the conversation on how to deal with a police interview, he didn't think to say, "Just tell them the truth as best you remember. We're innocent, after all."

Unknown to the jury, Case had much earlier communicated to Anastasia's family an incident in which he claimed to have been accosted by an individual he couldn't identify, who made a much less direct accusation against him, and to whom he repondeded much more directly.² For all of his excuses about why he didn't respond to his accuser's direct questions and accusations, he has never explained how he could evade one from someone who knew him after having so directly and strongly reacted to a less direct remark from someone he did not know.