Hours before the chairman of the House Intelligence Committee announced his shocking claims about surveillance of the Trump transition team on Wednesday morning, he practically disappeared.

Rep. Devin Nunes was traveling with a senior committee staffer in an Uber on Tuesday evening when he received a communication on his phone, three committee officials and a former national security official with ties to the committee told The Daily Beast. After the message, Nunes left the car abruptly, leaving his own staffer in the dark about his whereabouts.

By the next morning, Nunes hastily announced a press conference. His own aides, up to the most senior level, did not know what their boss planned to say next. Nunes’ choice to keep senior staff out of the loop was highly unusual…

Where Nunes went and who his source was for this information—which he said was still incomplete—is now a mystery with serious repercussions for the independence of his investigation into Russian interference with U.S. elections.