"Cop killers" are a type of bullet that can penetrate a police officer's body armor -- for example, a Kevlar vest. Cop-killer bullets have a stronger casing and a smaller bursting charge than regular bullets. Regular bullets are made of lead, which is considered a soft metal. Cop-killer bullets are made from stronger metals such as brass, steel, beryllium copper and iron. Cop-killer bullets are illegal for civilians to own, use or sell in most countries, including the United States and Canada.
> The 38-year-old police officer was shot and killed with cop-killer bullets, better known on the street as cop killers. Authorities do not know how the suspect in the murder obtained the illegal ammunition.