The first of two teenagers accused of setting a huge fire at the old Salem China factory in Salem will remain behind bars. The teen’s attorney filed a formal denial of the charges against him Wednesday. The filing is the juvenile court version of a not guilty plea. Prosecutors filed arson and breaking and entering charges against the suspect, who is a senior at Lisbon High School. He and another 17-year-old were arrested in connection with the fire that destroyed several warehouses that were once home to the property off of South Broadway and Euclid. The other suspect in the case, who is now under house arrest, is due in court later this week.