( CNN ) -- A member of a politically powerful family in the southern Philippines pleaded not guilty to dozens of murder charges filled against him in connection with a November massacre in Maguindanao province , Philippine news outlets reported . Datu Unsay Mayor Andal Ampatuan Jr. pleaded `` not guilty to all the 41 charges , '' Leila de Lima , chairwoman of the Philippine Commission on Human Rights , told reporters at Camp Crame where the trial is being held , CNN affiliate ABS-CBN said . Ampatuan could face an additional 16 charges in the Nov. 23 massacre that killed 57 people . Authorities have said the killings were part of a politically motivated attempt to keep an opponent of the politically powerful Ampatuan family from running for governor . Thirty journalists were among those killed . Authorities raided a warehouse and ranch belonging to the Ampatuan family last month and confiscated firearms , ammunition and vehicles , Maj. Randolph Cabangbang , deputy of operations for the eastern Mindanao command , said at the time . Following the killings , Philippine President Gloria Macapagal-Arroyo declared martial law on Dec. 4 before lifting it eight days later , saying it had achieved its objectives . Violence in the run-up to elections is not uncommon in the Philippines . The Maguindanao massacre , however , is the worst politically motivated violence in recent Philippine history , according to state media . The victims included the wife and sister of political candidate Ismael `` Toto '' Mangudadatu , who had sent the women to file paperwork allowing him to run for governor of Maguindanao . He said he had received threats from allies of Gov . Andal Ampatuan Sr. , the father of the accused mayor , saying he would be kidnapped if he filed the papers himself . Maguindanao is part of an autonomous region in predominantly Muslim Mindanao , which was set up in the 1990s to quell armed uprisings by people seeking an independent Muslim homeland in the predominantly Christian Asian nation .
Andal Ampatuan Jr. Mayor Datu Unsay pleads not guilty to murder charges . Charges filled against him in over Nov. 23 massacre in Mindanao . Authorities : Killings an attempt to stop Christian Asian opponent from running for governor . Nov. 23 massacre killed 57 people ; thirty journalists were among the dead .