Let's talk about an end to the McGonigal saga....

One of the highest-ranking FBI agents to ever face criminal charges was sentenced to over four years in prison on Thursday for secretly colluding with a Russian oligarch.

Charles McGonigal, a former counterintelligence leader in the FBI's New York field office, pleaded guilty to a conspiracy charge. McGonigal's lawyers had asked for no prison time, but the judge came down harshly on the former FBI bigwig.

"I committed a felony and as a former FBI special agent it causes me extreme emotional and physical pain," McGonigal told the judge prior to the imposition of the sentence. "I stand before you today with a deep sense of remorse."

Judge Jennifer Rearden paid tribute to McGonigal's "extraordinary contributions" to counterespionage operations on the country's behalf, but noted the "extraordinary seriousness" of his choosing to work for Oleg Deripaska, whom the U.S. sanctioned for enabling Russia's annexation of Crimea.