(S (S (BASENP (NN Two) (JJ 11-year-old) (JJ twin) (NNS brothers)) (VP (VBD were) (VP (VP (VP (VBN found) (S (VP (VBN stabbed)))) (PP (IN in) (NP (BASENP (PRPD their) (NN home)) (PP (IN in) (NP (BASENP (NNP Penn) (NNP Hills)) (COMMA ,) (BASENP (NNP Pennsylvania))))))) (PP (IN on) (BASENP (NNP Tuesday)))))) (PERIOD .))