FBI Director James Comey on Wednesday said former Attorney General Loretta Lynch’s tarmac meeting with President Bill Clinton in late June was the turning point in the investigation into Hillary Clinton’s use of a private email server.

Comey said the meeting aboard an airplane in Phoenix set off a series of events that ended with a bombshell revelation in the FBI director’s letter to congressional leaders 11 days before the November 8 election that the bureau would reopen the investigation.

During testimony on Capitol Hill before the Senate Judiciary Committee, Comey said “a number of things” had caused him to worry that Department of Justice leadership “could not credibly complete the investigation and decline prosecution without grievous damage to the American people’s confidence in the justice system.”

The “capper,” he said, was the meeting.

“I’m not picking on the attorney general, Loretta Lynch, who I like very much, but her meeting with President Clinton on that airplane was the capper for me,” he said. “And I then said, ‘You know what? The department cannot, by itself, credibly end this.'”