Naperville teacher Shaun Wild's death was caused by two stab wounds, a forensics expert said Friday.
But forensic pathologist Mitra Kalelkar testified that the 1.1-inch horizontal wound that perforated Wild's left lung and completely punctured his lower heart caused enough damage to be fatal on its own.
"There was massive bleeding into (Wild's) chest cavity and heart," Kalelkar told jurors during the trial of Donald Olaska, the Naperville man charged with killing Wild and stabbing two other men. "It would have had to have been a forceful thrust into the chest to cause these injuries."
Kalelkar said Wild also suffered a 2.5-inch-long and 2-inch-deep cut in his right forearm. While painful, Kalelkar said the forearm cut was not a fatal blow on its own.
Wild also had a "saw-toothed pattern" superficial wound on his right forearm that Kalelkar said could have been caused by the knife's handle.
Olaska, 30, of the 1500 block of Foxhill Road, is accused of stabbing Wild with a folding knife after stabbing Wild's friend, Willie Hayes, during a Feb. 4, 2012, confrontation at Frankie's Blue Room in downtown Naperville.
He has been charged with first-degree murder, attempted first-degree murder and unlawful use of a weapon.
At least one witness testified this week that Olaska stabbed Hayes in the chest with a 3½-inch folding knife after a heated discussion in which Hayes teased Olaska about drinking beer from a wineglass and Olaska criticized the tightness of Hayes' shirt.
Hayes testified earlier this week that he had no recollection of that interaction.
A doctor who treated Hayes on the night of the stabbing testified previously that his blood alcohol content was .206. Kalelkar testified Friday that Wild's most accurate level was .071.
Wild -- a 2011 North Central College graduate and second-grade teacher at Spring Brook Elementary School -- was stabbed in the heart when he tried to intervene, authorities said.
Rafael Castenada, who was working security at Frankie's, testified this week that Olaska cut a gash into his left forearm as he tried to detain Olaska following the stabbing of both Hayes and Wild.
Olaska's attorneys maintain Olaska stabbed Hayes in self-defense after he felt threatened during the encounter in the booth and further felt threatened when Wild attempted to prevent him from leaving the bar after Hayes was stabbed.
Prosecutors will resume their case at 9:30 a.m. Monday.