A police officer in Houston shot and killed a wheelchair-bound man Saturday; the double amputee only had one arm and one leg. Police say the man threatened the officer with a metal object that turned out to be a pen. A spokesman explained that Matthew Jacob Marin discharged his weapon after the man cornered him. Police did not release the name of the man who was killed, but the owner of the group home where he lived said he had a history of mental illness. Marin also fatally shot a suspect in 2009.