After UnitedHealthcare’s CEO was gunned down on a New York sidewalk, police searched for the masked gunman with dogs, drones and scuba divers. Officers used the city's muscular surveillance system. Investigators analyzed DNA samples, fingerprints and internet addresses. Police went door to door looking for witnesses. When an arrest came five days later, those sprawling investigative efforts shared credit with an alert civilian's instincts. A customer at a McDonald's restaurant in Pennsylvania noticed another patron who resembled the man in the oblique security-camera photos that New York police had publicized. Luigi Nicholas Mangione, a 26-year-old Ivy League graduate from a prominent Maryland real estate family, was arrested Monday in the killing of Brian Thompson, who headed one of the United States’ largest medical insurance companies. He remained jailed in Pennsylvania, where he was initially charged with possession of an unlicensed firearm, forgery and providing false identification to police. By late evening, prosecutors in Manhattan had added a charge of murder, according to an online court docket. He is expected to be extradited to New York eventually. MORE: https://www.wthr.com/article/news/nation-world/suspect-in-unitedhealthcare-ceo-killing-charged-with-murder/507-d21988f0-ec49-4e72-bbf2-d6bc0e8d9df6