A worker at a west Philadelphia abortion clinic has pleaded guilty to two counts of murder and may testify against Dr. Kermit Gosnell, the doctor accused of performing illegal late-term abortions, court officials said. Lynda Williams, a former employee of Gosnell’s Women’s Medical Society clinic, entered a guilty plea Wednesday to six charges, including two counts of third-degree murder. Williams is the fifth person to plead guilty in this case.