Questions & Answers about Hana grunar að lykillinn sé enn í handtöskunni.
Because gruna is used here in an impersonal construction. The person who has the suspicion is not put in the nominative case.
- hún = nominative she
- hana = accusative her
So Hana grunar ... literally uses hana, even though in English we translate it as she suspects ... or she suspects that ...
This is similar to other Icelandic verbs where English uses a normal subject, but Icelandic uses another case instead, such as:
- Mig langar = I want
- Mig vantar = I need / I am lacking
So here, hana is correct because gruna takes the experiencer in the accusative.