I was surprised last weekend when one of President Donald Trump's lawyers told my colleague Chris Wallace twice on "Fox News Sunday" that the president is being investigated by the FBI and then told him twice that he is not. This same lawyer repeated the "not being investigated" argument on a half-dozen other Sunday shows but did not repeat the "is being investigated" remark.

This produced substantial consternation in the news media and at the White House, since the President himself had tweeted over the weekend that he is being investigated for firing FBI Director James Comey by the same person — Deputy Attorney General Rod Rosenstein — who recommended Comey's firing and that the investigation is a "witch hunt."

So, who is correct, the president or his lawyer? Is the president under criminal investigation by the FBI? If he is being investigated as he claims, is the investigation a witch hunt? Here is the back story.

When Donald Trump began running for the Republican nomination for president in June 2015 and made novel arguments indicating that his view was that Europe should essentially pay for its own military defense, this triggered concern in European capitals, and it resulted in  the commencement of now well-documented British surveillance of Trump and his principal adviser on national security matters, retired Lt. Gen. Michael Flynn. The foreign surveillance was eventually passed on to American spies, who acceded to demands from the West Wing of the Obama White House and handed over transcripts of conversations and names of participants.

This went on throughout the presidential campaign and into the transition period after Trump had been elected. President Barack Obama's national security adviser, Susan Rice, recently confirmed that she ordered transcripts of surveilled conversations and names of participants — this is called "unmasking" in intelligence community lingo — and James Clapper, the Obama administration's director of national intelligence, recently acknowledged under oath the existence of the foreign and domestic surveillance of Trump in 2015 and 2016, as well as the unmasking.

One of the unmasked conversations handed over to Rice was between Flynn and the Russian ambassador to the U.S., Sergey Kislyak. Portions of that conversation were leaked to The Washington Post, and that generated interest in the relationship, if any, of the Trump campaign and transition team to the Russian government. This provoked a preliminary FBI investigation into Flynn. Flynn apparently was interviewed by the FBI while ignorant of the FBI's possession of transcripts of his conversations with Kislyak. If Flynn lied in that interview as has been reported and speculated in the press, he committed a felony. When Trump learned Flynn had lied to others, he fired Flynn.