Petty isn't playing Abby. If you had read the article and not just the headline, you would've realized that. They are playing the equivalent roles.

Moynihan will portray Woodrow “Woody” Browne, “the wildly overworked senior chemist and director of the NIS Forensic Lab, who compensates for his lack of sleep with an offbeat sense of humor.” Meanwhile, Petty will play Dr. Lenora Friedman, “a seasoned pathologist at the San Diego Medical Examiner’s Office."