United States — New York City Police Department & Luigi Mangione

United States — New York City Police Department: The United States — New York City Police Department investigated the murder of Brian Thompson and obtained intelligence reports indicating Luigi Mangione's motives.

Luigi Mangione: Luigi Mangione is the alleged perpetrator of the murder of Brian Thompson, driven by anger against the health insurance industry. His diary entries reveal meticulous planning and intent to cause fear and disruption in the industry.

United States — New York City Police Department: United States — New York City Police Department detectives are investigating Brian Thompson's killing and are receiving evidence from Altoona police.

Luigi Mangione: Luigi Mangione is the suspect in the murder of Brian Thompson and is currently fighting to exclude evidence from his murder case. His notebook expressed disdain for health insurers and ideas about killing a CEO.

United States — New York City Police Department: The United States — New York City Police Department was involved in the investigation, arrest of Luigi Mangione, and dissemination of suspect images. Their conduct during the arrest and search is a key point of contention in the defense's efforts to exclude evidence.