that was studied about because They knew his visible luggage .
(ROOT_0 (S_0 (ATS_3 (NP_1 (DT_1 that)) (VP_4 (VBD_1 was) (VP_2 (VBN_0 studied) (PP_2 (IN_0 about) (SBAR_0 (IN_2 because) (S_1 (NP_1 (PRP_0 They)) (VP_5 (VBD_0 knew) (NP_6 (ATNP_1 (PRPDOLLAR_0 his) (JJ_0 visible)) (NN_1 luggage))))))))) (DOT_0 .)))