By Steve Neavling
The FBI is investigating a friend of the San Bernardino shooters to determine whether he was involved or assisted in the attack, the Washington Post reports. 
Soon after the holiday party massacre, Enrique Marquez checked himself into a mental-health facility.
Authorities said he is cooperating and that Marquez acknowledged he was planning an attack with Syed Rizwan Farook in 2012 but backed off after four local men were arrested for plotting to kill Americans in Afghanistan.
Officials don’t believe he had prior knowledge of the holiday party attack, but he still faces the possibility of being charged.