Adjectives

(s)leery, mistrustful, suspicious, untrusting, waryopenly distrustful and unwilling to confide
(s)fishy, funny, shady, suspect, suspiciousnot as expected“there was something fishy about the accident”, “up to some funny business”, “some definitely queer goings-on”, “a shady deal”, “her motives were suspect”, “suspicious behavior”