(Portland, OR)  --  An ex-girlfriend of the man facing murder charges for allegedly killing his current girlfriend in Portland on Saturday says he threatened to kill her, too, when they were together.  According to a police report from last October, Spencer Johnson charged at his then-girlfriend with a gun in his hand, but police arrived and took it from him.  Now, Johnson is facing charges after police found the body of his girlfriend, Cory Lumber, last Saturday at the apartment they shared.  She died of a gunshot wound.