(S (S (SBAR (IN Although) (S (BASENP (PRP it)) (VP (VP (VBZ has) (RB not)) (VP (ADVP (RB yet)) (VP (VBN been) (VP (VBN proven) (SBAR (IN that) (S (BASENP (DT the) (NN poisoning)) (VP (VBD was) (ADJP (JJ deliberate))))))))))) (COMMA ,) (S (BASENP (NNS doctors)) (VP (VBP suspect) (SBAR (S (BASENP (PRP it)) (VP (VBZ was))))))) (PERIOD .))