He did so because one of the brothers did not have photo identification nor could he understand English, and because the agent found both of the passengers to be suspicious.
( He ( ( did ( so ( because ( ( one ( of ( the brothers ) ) ) ( ( did not ) ( ( have ( photo identification ) ) ( ( ( ( nor ( ( could he ) ( understand English ) ) ) , ) and ) ( because ( ( the agent ) ( ( found ( both ( of ( the passengers ) ) ) ) ( to ( be suspicious ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBD did) (SBAR (RB so) (IN because) (S (NP (NP (CD one)) (PP (IN of) (NP (DT the) (NNS brothers)))) (VP (VBD did) (RB not) (VP (VB have) (NP (JJ photo) (NN identification)) (SBAR (SBAR (SINV (CC nor) (MD could) (NP (PRP he)) (VP (VB understand) (NP (NNP English))))) (, ,) (CC and) (SBAR (IN because) (S (NP (DT the) (NN agent)) (VP (VBD found) (NP (NP (DT both)) (PP (IN of) (NP (DT the) (NNS passengers)))) (S (VP (TO to) (VP (VB be) (ADJP (JJ suspicious)))))))))))))) (. .)))
Both of the brothers were native English speakers.
( ( Both ( of ( the brothers ) ) ) ( ( were ( native ( English speakers ) ) ) . ) )
(ROOT (S (NP (NP (DT Both)) (PP (IN of) (NP (DT the) (NNS brothers)))) (VP (VBD were) (NP (JJ native) (JJ English) (NNS speakers))) (. .)))