(S (S (BASENP (JJ Last) (NN month)) (COMMA ,) (S (NP (BASENP (NN 57) (NNS people)) (PP (IN in) (BASENP (DT an) (NN election) (NN convoy)))) (VP (VBD were) (VP (VBN massacred) (PP (IN in) (NP (NP (BASENP (DT the) (JJ southern) (NN part)) (PP (IN of) (BASENP (DT the) (NNP Maguindanao) (NN province)))) (COMMA ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ has) (VP (ADVP (RB since)) (VP (VBN been) (VP (VBN placed) (PP (IN under) (BASENP (JJ martial) (NN law))))))))))))))) (PERIOD .))