CEDAR RAPIDS, Iowa (AP) — The jury in the first-degree murder trial a man accused of killing a woman in a Marion grocery store parking lot went home Friday without reaching a verdict.

Cedar Rapids television station KCRG reports that the jury is deliberating the fate of Nicholas Luerkens, who is accused of stabbing his ex-girlfriend, Lynnsey Donald, to death in April.

Police say Luerkens ambushed Donald while she was grocery shopping at the store, stabbing her more than a dozen times. During the trial, prosecutors showed store surveillance video that captured the attack.

The defense attorney argued that Luerkens was severely depressed at the time of the killing and, therefore, wasn’t fully responsible for his actions. Luerkens is seeking a conviction of the lesser offense of second-degree murder.