(S (S (PP (VBG According) (PP (TO to) (NP (BASENP (NNP Bierce)) (COMMA ,) (NP (BASENP (DT a) (NNP U.S.) (NNP Special) (NNP Agent)) (VP (VBG investigating) (BASENP (DT the) (NN incident))))))) (COMMA ,) (S (NP (BASENP (DT the) (JJ brutal) (NN attack)) (SBAR (WHNP (WDT which)) (S (VP (VBD saw) (S (S (BASENP (NNP Abeer) (NNP Qassim) (NNP al-Janabi)) (VP (VBN slain))) (CC and) (S (NP (PRPD her) (NP (BASENP (NNS parents)) (CC and) (BASENP (JJR younger) (NN sister)))) (VP (VBN murdered)))))))) (VP (VBD was) (VP (VBN premeditated))))) (PERIOD .))