Todd Mandoline and Paula Morgan fought over a necklace Mandoline had recently given her just hours be she died in a house fire he is accused of starting.
Mandoline, 25, is charged with first-degree murder, aggravated arson, arson and criminal damage to property after the July 22, 2012, fire he is accused of starting at 1028 S. Ahrens Ave. in Lombard.
Prosecutors say Mandoline admitted to police that he stuffed an ignited piece of a paper concrete bag into the gas tank of Morgan's mother's 2003 Acura just before 4 a.m.
Several witnesses testified Wednesday that Mandoline and Morgan were seen arguing, and even shoving each other, during Morgan's birthday party the night of July 21, 2012, as Mandoline insisted Morgan give him back a necklace he had given her earlier in the week as he attempted to rekindle their on again, off again relationship.
Morgan's best fried, Melissa Czarnik, 23, said Morgan called for her to intervene, but Mandoline told her to "stay out of it" and called her derogatory names.
Matt Schopa, a mutual friend of several partygoers, said Mandoline was seen "pushing (Morgan) and yelling at her" before another partygoer separated them and had words with Mandoline.
Schopa eventually volunteered to take Mandoline home to get him away from Morgan and the party -- but not before convincing Morgan to give him the necklace to calm Mandoline down.
"It was a party, and he was kind of obstructing the atmosphere of it," Schopa said.
Prosecutors said Mandoline then walked roughly two miles back to the party and stalked the house from the yards of a few homes away, waiting for Morgan's bedroom light to turn off before igniting the car in the driveway.
The fire quickly spread to the attached garage and home, killing Morgan, and severely injuring her friend, Jason Cassidy.
Former DuPage County forensic pathologist Jeff Harkey testified Wednesday that Morgan died of smoke inhalation and a lethal concentration of carbon monoxide in her blood.
Morgan's 6-year-old son, who was sleeping in the house, escaped the fire without injury and warned several other people in the backyard about the fire spreading from the front of the home.
Morgan's mother, Gina Morgan, who also lived in the house, wasn't home at the time.
She testified early Wednesday that she left earlier in the day to visit her parents in Indiana.
"Before I left, I gave her a kiss and said goodbye. That's the last time I saw her," Gina Morgan said through tears.
The trial resumes at 10 a.m. Thursday, with Cassidy expected to testify during the day. The trial is expected to carry into next week.