• Baffled U.S. investigators hope that Marilou Danley, who was in the Philippines when her boyfriend, Stephen Paddock, killed 58 people and injured hundreds in Las Vegas, can help explain what drove a man with no evident criminal history to become a mass murderer.

F.B.I. agents met Ms. Danley when she returned to the U.S. late Tuesday. They are also interviewing Mr. Paddock’s ex-wife, and trying to find “everyone and anyone” who crossed his path recently. Here are the latest updates.