Fingerprints, ballistics, Reddit writings: How the CEO death case evolved

Luigi Mangione's arrest this week over the fatal shooting of UnitedHealth Group Inc. executive Brian Thompson in Manhattan has failed to fill in some key details of the shocking killing that has gripped the U.S.

A national manhunt ended at a McDonald's restaurant in Altoona, Pennsylvania, where an employee recognized Mangione's face.

He was arrested in possession of a homemade gun, a pile of cash and a manifesto decrying the health care industry. He was locally charged with possessing an illegal gun and using fake identification. Far more serious charges came from authorities in New York, where he was quickly accused of second-degree murder and other crimes.

Mangione appeared in court, on Tuesday, with a lawyer to say he will fight the effort to move him back to New York, touching off legal wrangling that could take weeks to play out.

Investigators were able to match the gun Mangione carried at the time of his arrest to the weapon used to kill Thompson with three spent shell casings that were found at the scene outside the Hilton Hotel in Midtown, New York City Police Commissioner Jessica Tisch said at a news conference, on Wednesday.

The New York Police Department's crime lab was also able to match Mangione to fingerprints found on both a water bottle and an energy bar recovered near the scene, she said.