"The husband and wife responsible for killing 14 people in a shooting in San Bernardino this week tried to illegally modify a semi-automatic rifle to turn it into a machine gun, federal authorities said Friday. A Smith & Wesson M&P15 found with the couple after a gun battle with police Wednesday was altered in an attempt to enable the weapon to be fired automatically, said Meredith Davis, a spokeswoman for the federal Bureau of Alcohol, Tobacco, Firearms and Explosives. The modification is illegal under federal law, she said. Initial tests, she said, show that the modification did not work and the gun could not be fired automatically, Davis said. She said more tests were yet to be done. A DPMS Model A-15 rifle also found with the couple after the shootout had been altered to accept a high-capacity magazine that is illegal under California law, she said."