“I’ve had a lot of classified briefings on it, and it’s deeply troubling,” Katko told syracuse.com in an interview Tuesday. “I was left with a profound sense that it was much worse than people realized.”

Katko would not discuss any specific information he received. But he said the briefings from federal authorities were enough to convince him that Congress needs a 9/11-style commission to investigate and subpoena witnesses.

“There are a lot of unanswered questions here, from possible security lapses to who was involved and when they were involved,” Katko said. “We need to have a full stem to stern look back on this to see what happened, how it happened, the sequence of events, who contributed to it, and how we make sure it never happens again.”