REVERE – Additional charges have been filed against a Quincy man already accused of sexually assaulting a 5-year-old girl in his care following a two-month investigation, according to District Attorney Daniel Conley.Sergio Lara, 53, is charged in a six-count indictment with rape of a 5-year-old child, indecent assault and battery on a second 5-year-old, and two counts each of disseminating matter harmful to minors and open and gross lewdness for incidents involving two boys, ages 8 and 9.Lara was arraigned on those charges Monday at Suffolk Superior Court and ordered held without bail pending a bail review sought by his attorney.On March 2, Revere police arrested Lara and he has been in their custody since then. Lara is the owner and operator of Maya Transportation, which shuttles children to and from schools and daycare centers in Revere, Chelsea and East Boston.During Monday’s court hearing, Assistant District Attorney Mindy Klenoff told Clerk Magistrate Gary D. Wilson that Lara came to authorities’ attention in early March after the first victim told her mother about the alleged abuse.In that case, Klenoff said Lara picked the girl up from daycare on March 1 and, after driving the other children home, allegedly drove her to an undisclosed location and sexually assaulted her. He then allegedly instructed her to not tell anyone what had happened and promised that he would buy her favorite candy the next day and drove her home.The girl then reported the alleged assault to her mother, who took her to the hospital and notified Revere police and the daycare provider. Revere detectives began their investigation and the daycare provider suspended Lara.The following day, the mother of another 5-year-old girl who rode in Lara’s minivan heard about the allegations.”Taking care not to mention the defendant’s name,” Klenoff said, “the mother asked her daughter if anyone had touched her private parts. The girl responded that Lara had done so and that she didn’t like it.” That mother then reported the abuse to police.Klenoff told the court that during the course of the investigation, prosecutors learned of two young brothers who rode in Lara’s van on separate occasions.Both alleged victims told the authorities that he had shown them pictures of naked women on his cellular phone and had masturbated in front of them in the minivan.Lara is represented by attorney Christopher Coughlin, with Kathryn DiPerna as the DA’s assigned victim-witness advocate. Lara’s next scheduled court date is July 15.