The National Post reports in its Tuesday edition that police arrested a suspect Monday in the brazen Manhattan killing of Unitedhealth's chief executive officer after a quick-thinking McDonald's employee in Pennsylvania alerted authorities to a customer who was found with a weapon, mask and writings linking him to the ambush. An Associated Press dispatch to the Post says that the chance sighting at the restaurant in Altoona led to a dramatic break in a challenging but fast-moving investigation that had captivated the public in the five days since the shooting that shook the health insurance industry. The suspect, identified by police as 26-year-old Luigi Nicholas Mangione, had a gun believed to be the one used in last Wednesday's shooting of Brian Thompson, as well as writings suggesting anger with corporate America, police said. Mr. Mangione was taken into custody about 9:15 a.m. after police got a tip that he was eating at a McDonald's in Altoona, police said. Mr. Mangione had clothing and a mask similar to those worn by the shooter and a fraudulent New Jersey ID matching one the suspect used to check into a New York hostel before the shooting. Police said they found on him a three-page handwritten document.