And making the maximum sentence 48 years.
Felony murder is in most states (not Montana where it has been broadened to include considerably more) is the law that allows the State to prosecute an individual for a death that occurred in the course of a felony, even if the person didn’t commit the homicide themselves. For example the getaway driver in a bank robbery can be held responsible for a death caused by one of the active participants in the robbery (or potentially the death caused by a security officer or law enforcement that gets involved).