Part of the gun that the police believe was used to kill the C.E.O. of UnitedHealthcare was made by a 3D printer using a popular design found online. By Thomas Gibbons-Neff and Aric Toler At first ...

More than a decade after the advent of the 3D-printed gun as an icon of libertarianism and a gun control nightmare, police say one of those homemade plastic weapons has now been found in the hands of ...

For decades, America's detectives have made breakthroughs in crime using gun traces. A homicide investigator typically uses ballistics and serial numbers of weapons checked via a vast network of gun ...