criminal investigation squad; investigation team
Refers to a group or team assembled for a criminal investigation, often used in news reports or police contexts.
The police quickly formed an investigation team.
The investigation squad arrived at the scene.
捜査員 is an individual investigator, whereas 捜査陣 is the collective group or squad.
Compound of 捜査 (investigation) and 陣 (camp, formation, team). The suffix 陣 is often used to denote a group or team assembled for a specific purpose.