(S (S (NP (QP (ADVP (IN At) (JJS least)) (NN one)) (BASENP (NN eyewitness))) (VP (VBZ claims) (S (VP (TO to) (VP (VB have) (VP (VBN watched) (S (BASENP (NNP Semrau)) (VP (VP (VBG shooting) (BASENP (DT the) (NN militant))) (PP (IN with) (BASENP (PRPD his) (NN field) (NN rifle))))))))))) (PERIOD .))