"Then I think the prosecution will combine both cases, and each case will sort of feed off the other and will present a powerful picture to both a trial judge and a jury that this guy is a serial murderer," legal analyst Dana Cole told ABC's "Good Morning America" last week.
Peterson told "Today" that he will "probably be found innocent" of Savio's murder.
Brodsky has aid he expects to challenge a new Illinois state law that could prove vital to the prosecution's case.
Prosecutors are hoping they can enter into evidence writings from Savio when she was in the midst of her divorce from Peterson, that she feared her husband's "next step is to take my children away or kill me."
A new Illinois state law allows such statements only if the witness was killed to prevent him or her from testifying.
The Associated Press contributed to this report.