suspect
Detectives often suspect suspect dealings in corruption cases.
The sentence describes how detectives often believe questionable activities exist in cases involving corruption.

Meanings
to believe or surmise that something is the case, often without proof
- I suspect she's been working harder than she lets on.
- Detectives suspected an inside job.
as adjective: questionable, dubious, or arousing distrust. As noun: a person believed to be guilty of an offense
- The accountant's books looked suspect.
- Police released the suspect's photo.
Word origin
From Latin suspectus, past participle of suspicere ('to look up at, regard with awe — also, to look askance at, mistrust'), formed from sub- ('up from below') + specere ('to look at'). The same root specere underlies 'spectator', 'inspect', 'aspect', 'respect', and 'spectrum'. The verb-adjective stress alternation follows the trochaic noun rule.
Fun fact
The Latin specere ('to look') is one of the most productive roots in English — 'spectator', 'inspect', 'respect', 'aspect', 'suspect', 'introspection', 'spectacle', 'spectrum', 'spy' (via Old French). All involve looking in some direction or manner. To 'suspect' is literally 'to look up from below' — i.e., warily, sideways, with mistrust.