Alan Dershowitz expressed doubt on Monday that federal prosecutors could make a case for attempted murder against the man accused of trying to assassinate former President Donald Trump on Sept. 15.

Secret Service agents thwarted the apparent assassination attempt on Trump by firing shots at Ryan Wesley Routh, who was allegedly lurking near Trump International Golf Club, two months after Trump was shot in the right ear while giving a speech at a July campaign rally in Pennsylvania. Dershowitz said that despite Routh’s intent to kill Trump, it was not clear that all of the legal elements for attempted murder were present.

“Based on my experience, I don’t think they have a case for attempted assassination,” Dershowitz said. “Let me explain why, this is gonna sound so counterintuitive. The guy obviously wanted to kill the president and he took actions to kill the president. Now here… you’re getting a free Harvard criminal law class.”

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“If he conspired with somebody else to do, it would be an open and shut case, because for conspiracy all you need is an agreement to kill the president or to try to kill the president, and he did certainly agree with himself, he certainly made up his mind,” Dershowitz continued. “We have the evidence, the letter, he wrote a letter… saying ‘I wanted to kill the president, I tried to kill the president, I failed, I’m giving $150,000 to anybody else who succeeds.’ So, if it were conspiracy, it would be a clear case, conspiracy to assassinate the president, open and shut. Why isn’t it an open and shut case for attempt?”

Federal prosecutors released Routh’s letter in a Monday court filing.

“Criminal law distinguishes between preparation and attempt. Now, there’s no question: He prepared to kill the president,” Dershowitz said about Routh’s alleged actions. “He did everything he could to do it. He got the gun, he got the ammunition, he got the scope, he surveilled… he sat in the bushes and, of course, and to make this clear, the first guy who try to kill the president, who was killed, there was clearly an attempt. He fired a gun. He aimed at the president, fired at him and hit him in the ear. The clearest possible case of attempted murder.”

“He never had the president in his line of fire, and of course he never pulled the trigger,” Dershowitz said, referring to Routh. “So the question as the court will have to address, the question without a clear answer, is whether or not preparing, putting your gun in a location, putting it through the link fence, but not getting the president in the line of sight and not pulling the trigger is enough to turn it from preparation to attempt, and the law is just unclear on that.”