Police say UnitedHealthcare's CEO was likely killed with a ghost gun. What are they? Police say the suspect had a ghost gun, possibly made with a 3D printer, when he was arrested on Monday. Here's what to know about the increasingly widespread weapons and efforts to regulate them. Rachel Treisman
Arctic tundra now emits planet-warming pollution, federal report finds Arctic tundra is releasing greenhouse gases into the atmosphere as hotter temperatures melt frozen ground and wildfires increase. Barbara Moran
'We're absolutely in panic mode': Toymakers are bracing for Trump's tariffs Toy companies are preparing for tariffs in the new Trump administration. Nearly all toys sold in the U.S. are imported — mostly from China. Scott Horsley
A phone company developed an AI 'granny' to beat scammers at their own game The company behind the scam-baiting granny said the AI technology can keep scammers on the phone for 40 minutes at a time, keeping them away from real people. Alana Wise
A suspect holding a handwritten manifesto is charged in the UnitedHealthcare CEO shooting Luigi Mangione, 26, was arrested and charged with murder on Monday. He was found at a McDonald's in Pennsylvania, but is expected to be extradited to New York. Ayana Archie
Florida prosecutor seeks to overturn convictions in cocaine sting operation A Florida prosecutor says he will seek to vacate as many as 2,600 convictions of people who bought crack cocaine made by the Broward County Sheriff's Office for sting operations between 1988 and 1990. The Associated Press
Lawsuit: A chatbot hinted a kid should kill his parents over screen time limits Two families are suing AI chatbot company Character.AI for allegedly encouraging harm after the kids became emotionally attached to the bots. One chatbot allegedly exposed a child to sexualized content. Bobby Allyn
Taller vehicles are more dangerous to pedestrians, even at low speeds, research finds A study by the Insurance Institute for Highway Safety shows higher speeds are worse for pedestrians regardless of vehicle height — but those risks are amplified for vehicles with taller front ends. Joel Rose
What we know about Luigi Mangione, the suspect in United Healthcare CEO's killing Mangione was arraigned on firearms and forgery charges in Pennsylvania after his arrest Monday evening, and is expected to face charges in New York as well. Maria Aspan
