WASHINGTON — A Navy contractor who shot 12 people to death at the Washington Navy Yard left a cryptic message on a shotgun he used in the massacre. That’s according to a law enforcement document reviewed by The Associated Press.

The document says the messages were — quote — “better off this way” and — quote — “my ELF weapon.” The document also described the Remington shotgun as “sawed off”

Aaron Alexis, a former Navy reservist, went on the shooting rampage Monday morning, killing 12 people at the Navy base before being killed by authorities responding to the scene.

Alexis had been seeking treatment from the Veterans Administration for severe mental health problems. He bought the shotgun legally at a Virginia gun shop on Saturday.