Former President Donald Trump's Mar-a-Lago residence in Florida was raided following a tip-off that classified government documents may have been improperly stored at the property.Brandon Bell/Getty Images Mick Mulvaney said that someone "very close" to Trump is possibly working with the FBI. Mulvaney, who was Trump's chief of staff, said even he didn't know there was a safe at Mar-a-Lago. He estimated there were six to eight people in Trump's inner circle with access to such information. Former Trump White House chief of staff Mick Mulvaney has speculated that if an FBI informant in Trump's camp did exist, they would likely be one of the six to eight people closest to the former president.Mulvaney spoke to CNN on Thursday about the FBI's Monday raid of Trump's Mar-a-Lago residence in Florida.He said that he thought the informant whose tip-off sparked the raid was likely someone deeply embedded in Trump's orbit and "really close" to him.Citing sources, Newsweek and The Wall Street Journal reported on Wednesday that someone had told the authorities that classified government documents might have been improperly stored at Mar-a-Lago."I didn't even know there was a safe at Mar-a-Lago, and I was the chief of staff for 15 months," Mulvaney said.