(S (S (ADVP (BASENP (NN Three) (NNS days)) (RBR later)) (COMMA ,) (S (BASENP (NNP The) (NNP Continuity) (NNP IRA)) (VP (VBD claimed) (NP (BASENP (NN responsibility)) (PP (IN for) (NP (BASENP (DT the) (NN murder)) (PP (IN of) (NP (NP (NP (NP (BASENP (NNP Police) (NNP Service)) (PP (IN of) (BASENP (NNP Northern) (NNP Ireland)))) (NN officer)) (BASENP (NNP Stephen) (NNP Carroll))) (COMMA ,) (SBAR (WHNP (WP who)) (S (VP (VBD was) (VP (VBN shot) (PP (IN by) (NP (BASENP (DT a) (NN sniper)) (VP (VBG responding) (PP (TO to) (BASENP (DT a) (NN call)))))))))))))))))) (PERIOD .))