(S (S (NP (BASENP (DT The) (NN investigation)) (PP (IN into) (NP (BASENP (DT the) (NN plane) (NN crash)) (SBAR (WHNP (WDT that)) (S (VP (VBD killed) (BASENP (JJ Polish) (NNP President) (NNP Lech) (NNP Kaczyński)))))))) (VP (VBZ has) (VP (VBN revealed) (SBAR (IN that) (S (BASENP (NNS passengers)) (VP (VBD were) (PP (IN in) (NP (BASENP (DT the) (NN cockpit)) (PP (IN of) (BASENP (DT the) (VBN crashed) (NN plane))))))))))) (PERIOD .))