We want phrases to describe suspicious not sentence

Someone or something not suspicious: trustworthy or trusted.

Someone not feeling suspicious : trusting, unwary

'Suspicious' is an adjective, it doesn't have a past tense.

We say "acting suspicious" to describe someone's behavior or actions that seem questionable or cause concern. On the other hand, "looking suspicious" may refer to someone's appearance that suggests potential wrongdoing, but the more common phrase is "acting suspicious."

Suspicious characters do a lot of lurking about...