Is an internship important if I’m interested in a forensic career which requires a higher degree (such as pathology, anthropology, odontology. . .)?
No, an internship is not as necessary, but some kind of experience at the undergraduate level in the area to which you are applying for graduate school is always a good idea. This could be anything from an undergraduate teaching assistantship to a volunteer position to a senior thesis—but such experience makes your graduate application stronger.