SAN FRANCISCO -- Jury selection is underway in the trial of a man and woman charged in the fatal stabbing of a San Francisco construction worker, who was killed after a dispute over whether the suspects could use a portable restroom.Lizette Maria Cauich, 25, is accused of fatally stabbing construction worker Mitzi Campbell, 58, in the city's South of Market neighborhood on June 10, 2016.Campbell, a San Francisco resident who was working as a flagger controlling traffic at a construction site on Shipley Street, was stabbed shortly after 9 a.m. after an argument with Cauich and her co-defendant Oscar Mendez over whether the two could use a portable restroom there.She escorted Cauich and Mendez, 44, off the site but when she didn't return right away, her co-workers checked on her and found her suffering from stab wounds.Campbell died of her injuries at a hospital a short time later, while Cauich and Mendez were arrested nearby in the area of Fifth and Folsom streets.After their arrest, prosecutors said the pair had also been involved in an attack on May 29, 2016, in which they both allegedly stabbed a man at a parking lot at Eddy and Taylor streets, also after he refused to let them use a portable restroom on the site.The victim in that attack was seriously injured but ultimately survived after fending the pair off with a garbage can lid and fleeing through the streets of the Tenderloin toward a police station, according to prosecutors.Cauich is charged with murder, attempted murder, mayhem, assault with a force likely to cause great bodily injury, attempted robbery and battery with seriously bodily injury, and remains in custody with bail set at $10 million.Mendez is charged with attempted murder, mayhem, assault with a force likely to cause great bodily injury, battery with serious injury, carrying a dirk or dagger, possession of a controlled substance, receiving or buying stolen property, and giving false information to a police officer. He also has previous felony warrants and is being held without bail.Jury selection is underway in the case, and opening statements could start as soon as this week.