Suspeculate
Having intuitions of both suspicion and speculation of a questionable event, person, or story.
Knowing what a liar Jack was, I suspeculate his story of spotting Elvis was bullshit.
suspeculate
The act of speculating about someone or something you suspect to have done something good or bad (usually bad)
Timmy suspeculated that the hairy man in the minivan had to be the one who stole his pez dispenser collection.