The former Bollingbrook Police sergeant is on trial for the death of his third wife, Kathleen Savio.
His fourth wife, Stacey Peterson, has been missing for five years and the defendant is considered a person of interest in that case.
After the prosecution rests, the first move the defense will make is asking the judge for a directed verdict. Peterson's lawyers will argue that the state has not presented enough evidence, so the judge must find Peterson not guilty.
If the judge wants the jury to decide, the case continues. The defense says it will call a handful of witnesses. Their client is not likely going to be one of them.
Among the remaining questions is whether Peterson will take the stand. If his defense team has their way, the former he will stay put. However, by law, a defendant has the final say.
"If he really wants to, we can't stop him but he has expressed an interest, we will see what happens," said Peterson lead attorney Joel Brodsky.
Brodsky says there is no reason for Peterson to testify on his own behalf because he says the state has not presented any evidence that Peterson needs to explain.
"They haven't put him anywhere near that house in that house all we have is some pretty bizarre sounding hearsay about night Kathy died," Brodsky said.
Savio was found dead in her dry bathtub.
If the 58-year-old Peterson chooses not to take the stand, the jury will be instructed not to hold that against him. Despite that, IIT Kent School of Law professor Susana Ortiz says in her experience, juries like to hear from the defendant.
"In juries I've spoken to after trials, they will be candid and say will say I wanted to hear person say they didn't do it," she said.
The defense maintains Savio's death was an accident, as it was originally ruled in 2004 before it was reclassified as a homicide after Savio's body was exhumed.
Besides calling police officers, the defense plans to present their own medical experts to dispute prosecution pathologists who testified the Savio was murdered and there is a chance Peterson's lawyers will call Savio's divorce attorney, Harry Smith.
"We'll get through everything done in our case including doctors in two days," Brodsky said.
The defense is under no legal obligation to present a case. The burden of proof is all on the prosecution. However, Brodsky says calling defense witnesses is necessary to clarify a few points made during the state's case.
Prosecutors can call rebuttal witnesses after the defense is done with its case.