If you are talking about science, technology or academia, you would either say 'a team of researchers' or use the compound noun 'a research team'. 'Team' is a better word than group, because 'group' suggests that they aren't really working together. If they are collaborating closely, and each person has their own role, you would call them a 'team'. 'Investigators' is mainly used in police, crime, and legal contexts.

You can translate it well and literally as "a team of investigators" e.g. a group of police searching a crime scene.