There is no physical evidence connecting the former Bolingbrook police sergeant to the death of third wife Kathleen Savio.
Closing arguments will be the attorneys' last chance to sway jurors.
"If the state can't prove it's a homicide, without a reasonable doubt, it doesn't matter what people said. It doesn't matter what Rev. Schori said, it doesn't matter what the sister said, it doesn't matter what anybody says, because if they can't prove it's a homicide, it has to be a not guilty," said Joe Lopez, who will speak for the defense.
Savio was found in a dry bathtub in 2004. Her death was originally ruled accidental, but investigators reopened the case after Peterson's fourth wife, Stacy, disappeared in 2007.
Peterson denies any wrongdoing.