A Pennsylvania man who claims mood swings from an acne drug caused him to fatally stab a 16-year-old cheerleader has been convicted of murder.

The Allegheny County jury took fewer than two hours on Monday to convict 20-year-old John Mullarkey Jr., of Monroeville, of killing his ex-girlfriend Demi Cuccia in 2007.

Mullarkey's attorney had asked earlier for a mistrial because Hoffmann-La Roche Inc., of Nutley, N.J., pulled Accutane off the market Friday citing concerns over pricing of a generic version and other issues.

But Judge Jeffrey Manning said the trial wasn't tainted because the company's decision had nothing to do with the defense's claims that Accutane affected Mullarkey.

Mullarkey's attorney has acknowledged his client stabbed Cuccia but says it wasn't premeditated.