Thomas Zich has been found guilty of murder on Wednesday and sentenced to 15-years to life for the strangulation death of his wife in 1991.
Zich, 62. was on trial for killing his wife, Mary Jane Zich, and stuffing her body into a car trunk in December 1991.
The jury reached a decision after four hours of deliberations.
Attorneys for both sides wrapped up closing arguments on Wednesday morning before Judge Gene Zmuda sent the case to the jury.
On Tuesday, both sides rested their case. Prosecutors had sought to have Zich's step-daughter testify. She was three-years old at the time of the murder and claims that she saw Zich stuff the body of his wife in a trunk.
When she was 3 years old, Desiree Andaverde told police she saw the killing. The woman, now 20, told police before her mother's body was found that she watched "daddy put mommy in the trunk," prosecutors said before the trial began.
Defense attorney Alan Konop had unsuccessfully argued in pretrial hearings that her testimony should not be allowed because the memory of such a young child is unreliable and that her impressions of what happened may have been influenced by family members over the past 17 years. The defense also said she made inconsistent statements.
The jury did hear testimony that the defendant, Thomas Zich, told police two years ago that the marriage had been fine, contradicting what he told others. A woman who briefly dated Zich said he told her several times before his wife's body was found that his marriage was over and that his wife wasn't coming back.
On Tuesday, they listened to a recording of a police interview with Zich in which he told investigators that he and his wife never talked about divorcing. He also said that he had no idea his wife was seeing another man and never caught her with someone else.
But witnesses who testified earlier said that Zich once found his wife with another man and knew she was cheating.
Luann Urbanski, who became friends with Zich before his wife disappeared, said that the two often talked about the Zichs' worsening relationship. Urbanski said that Zich knew they would divorce and was worried that his wife would get half of his money and the rental properties they owned.
"He said he wasn't going to let that happen again," she said.
The defense rested without calling any witnesses.
The case was documented by NBC "Dateline" for a future broadcast.