Chen faces two counts of aggravated first-degree murder. He admitted to killing the victims, whose bodies were found with fatal stab wounds inside the family’s apartment, after he’d answered the door to that apartment naked and covered in blood in 2011.
An analysis of Chen’s blood showed he had the cough suppressant dextromethorphan, the anti-anxiety drug Xanax, and an antihistamine in his system. Experts say that cough syrup can cause intoxication, and that the effectiveness of Chen’s “diminished capacity” defense, which can be considered when evaluating a defendant’s state of mind, will depend on whether Chen became intoxicated voluntarily.
According to court documents, Chen’s attorneys’ might rely on scientific research showing that people of Asian descent metabolize certain drugs differently than people of other ethnicities.