Anna Doman, the sister of Kathleen Savio, was on the stand when the proceedings were halted Friday afternoon.
Peterson is on trial for the first degree murder of his third wife, Savio, in 2004.
The ill juror was coughing so badly it was difficult to hear the Attorneys, so Judge Edward Burmila dismissed the court, but not before the court heard the first hearsay testimony of the case.
Doman told the court her sister, Kathleen Savio, feared for her life six weeks before she was found dead. Doman testified that Savio told her, "Drew said, 'I'll kill you and you will not live to see the divorce settlement.' " It is the first time hearsay testimony was used in this trial.
Prosecutors argue the defendant, Drew Peterson, was determined to keep his third wife, Kathleen Savio, from getting half of his annual pension after retiring from the Bolingbrook Police Department.
Peterson is accused of drowning Savio during their divorce proceedings. Her body was found in her dry bathtub. Authorities first ruled her death an accident, but when Peterson's fourth wife, Stacy, disappeared in 2007, investigators reopened the case and re-examined Savio's body and determined it was a homicide.
Doman told the court, her sister "Kitty," as she called her, asked her to care for her two sons if she died, but she never reached out to the boys after Savio's death.
The defense called an often flustered and confused Doman a liar.
"If you tell the truth, you don't have to remember what you said," said defense attorney Joel Brodsky. "Only a liar has to remember what they said, and she can't seem to keep it straight."
Prosecutors focused on a request from Savio to her sister to remove a briefcase with documents from Savio's SUV in the event of her death, paperwork she didn't give to authorities until years later.
When the defense grilled Doman on why, if she knew about an alleged threat, she didn't turn to police, she said they didn't listen to her or her family.
"No one would listen," Doman said. "No one would listen, I tried."
The state remains confident they can prove wrongdoing by Peterson.
"I'm confident that at the completion of our evidence, the total picture will be there," said Will County State's Attorney James Glasgow.
Judge Burmila said court will resume Tuesday morning so the juror can have time to recover. He said he hopes with this early dismissal no other jurors catch the illness.