suspiciously
adv.in a way that makes you feel like something is wrong or that someone is lying. You use this when someone's behavior or a situation seems strange and untrustworthy.
adv.in a manner that suggests guilt, dishonesty, or something wrong; alternatively, used to describe a state that arouses doubt or mistrust in others.
“The man was looking suspiciously at the locked door.”
“The car was parked suspiciously close to the bank entrance with the engine still running.”
“Although the witness claimed to be at home during the incident, her suspiciously detailed account of the weather suggested she had rehearsed her alibi.”
Typically follows the verb it modifies, though it can appear in the sentence-initial position to set a tone of doubt for the entire clause.
“Only then did Parkinson notice a suspiciously clean, straight wound on the back of the caiman's head, possibly caused by a blow from a speeding boat, he suspects.”
“Relatives also told Essex police that he was behaving suspiciously and they believed he was guilty.”
From suspicious + -ly.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.