あの人の動機が信用できなかった。

that (someone or something distant from both speaker and listener, or situation unfamiliar to both speaker and listener)

man; person; human being; mankind; people; human (Homo sapiens); humans as a species; character; personality; man of talent; true man; another person; other people; others; adult

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

motive; incentive; motif

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

confidence; dependence; credit; faith; reliance; belief; credence; trust

to be able (in a position) to do; to be up to the task; to be ready; to be completed; to be made; to be built; to be good at; to be permitted (to do); to become intimate; to take up (with somebody); to grow; to be raised; to become pregnant