Learn German: Der Forscher hat gestern ein Artefakt gefunden. - The researcher found an artifact yesterday.

To express a strong subjective assumption about a past event using dürfen, you use its Konjunktiv II form (dürfte) along with the past infinitive of the main verb (gefunden haben). The sentence would become: Der Forscher dürfte gestern ein Artefakt gefunden haben.

Why does the time word gestern come before the object ein Artefakt?

German generally prefers to place time information before noun objects. This is part of the standard word order guidelines (often taught as "TeKaMoLo"). Adverbs of time like gestern naturally sit early in the sentence's middle section, safely ahead of a direct accusative object like ein Artefakt.

Could I use der Wissenschaftler instead of der Forscher here?

You could, but der Forscher is often a better fit for this specific context. While Wissenschaftler means "scientist" or "academic" in a broad, often theoretical sense, Forscher highlights the investigative, exploring, or discovering aspect of research—perfect for someone out in the field uncovering physical objects.

What is the gender of Artefakt, and is there a rule to help remember it?