3D-printed ghost guns pose new threat in US

Homemade weapons without serial numbers increasingly used in crimes

They look like toy guns, are part plastic and resemble LEGO pieces — yet they are lethal. They are 3D-printed ghost guns, and they are increasingly being found in the United States and used in high-profile crimes.

The guns are hard to trace as they are often homemade, without serial numbers. They can be either partially or completely made with components that have been produced as metal or plastic, on commercially available 3D printers.

In December, police said that Luigi Mangione had used a 3D-printed gun in the fatal shooting of United-Healthcare CEO Brian Thompson, the first known assassination in the US involving such a weapon.