Nearly a month has passed since Stephen Paddock opened fire on a country music festival at the Mandalay Bay Resort and Casino in Las Vegas, killing 58 people and wounding hundreds more — yet the shooting continues to confound the public and investigators alike. Little is known about Mr. Paddock’s motives. And investigators have revised parts of the timeline of the shooting on three occasions, raising further questions about what exactly happened.



During continuing investigations into major events, traditional reporting often relies in part on official statements from law enforcement officers. But in this case, faced with shifting reports, The New York Times wanted to try to establish a timeline independent of that offered by the Las Vegas Metropolitan Police Department.

The Times’s video unit, where I am a producer focused on visual and open data investigations, turned to a relatively new technique: investigative video reporting, or so-called video forensics, pioneered and developed by a small community of human rights groups and niche social journalism outlets over the last decade. Its greatest value is in documenting hard-to-reach places like war zones, but the tools can be used wherever there’s an abundance of visual evidence. (In May, a Times video debunked Syria and Russia’s claims about a chemical weapons attack; in June, another video identified 24 men, including members of the Turkish president’s security detail, who attacked protesters outside the Turkish ambassador’s Washington residence.)