Thirty-seven-year-old Brian Cooper of Plainfield, Illinois, faces two counts of first-degree intentional homicide in the strangulation of 21-year-old Alisha Bromfield in August 2012. Cooper's first trial ended in a hung jury last year.
In opening statements Monday, prosecutor Raymond Pelrine told jurors that Cooper was in love with Bromfield and "If he couldn't have her, no one could."
The Door County Advocate reports the defense countered that although Cooper was not the baby's father, the two did have a romantic relationship at one time.
Bromfield accompanied Cooper to attend his sister's wedding on the peninsula that weekend.
The retrial is expected to last most of the week.