Update: A good follow-up question for Consovoy would have been, "Okay, forget about 5th Avenue then. Suppose Trump is at his impeachment trial, and he pulls out a gun and shoots 20 Democratic Senators before they can vote to impeach him. Still can't do anything about it?"
Last week CNN and a number of other news outlets reported an exchange between Trump's personal attorney William Consovoy and federal appellate judge Denny Chin in which Trump's attorney affirmed his belief that Trump could in fact shoot someone on Fifth Avenue and still be immune from prosecution.
However, I couldn't find any transcript conveying the exact words of the exchange, which involved Consovoy, Chin, and Manhattan District Attorney Carey Dunne.
Happily, oral arguments before the Second Circuit Court of Appeal are recorded and publicly available here (look for Trump v. Vance, 19-3204, October 23, 2019).
For convenience, here is my edited transcript of the relevant portions of the exchange:
Court (to Consovoy): "Your position as you said a moment ago is that the immunity is absolute. And so if the President were to commit a crime, no matter how heinous, whether he did it before he took office or whether he did it after he took office, he could not be the subject even of an investigation? That's your position?
Consovoy: "Yes. Of course Congress still retains the impeachment power. And on the other side of impeachment, as the Constitution makes clear, the President, like all other citizens, is subject to the laws and jurisdiction of states and the federal government alike.
...
Court (to Dunne): Can I ask you about absolute immunity to criminal prosecution while a President is in office? Do you agree that there is some immunity from a criminal trial while he or she is in office?
...
Dunne: You can invent scenarios where you can imagine that it would be necessary, or perhaps it would be a good idea, for a sitting President to be subject to a criminal charge, even by a state, while in office. If, for example, he did pull out a handgun and shoot someone on Fifth Avenue, what would be the impact of that? Would local police be disabled from restraining such a person, or processing such a person? Would we have to wait for an impeachment proceeding to be initiated?
...
Court (to Consovoy): What's your view on the 5th Avenue example? Local authorities couldn't investigate, they couldn't do anything about it? Consovoy: Once a President is removed from office, any local authority -- this is not a permanent immunity. I'm talking about while in office.
Court (to Consovoy): That's the hypothetical, while in office.
Consovoy: No.
Court (to Consovoy): Nothing could be done. That's your position.
Consovoy: That is correct.
Court (to Consovoy): So even gathering documents that could be used later, once the President leaves office -- that can't be done either?
Consovoy: ...That can't be done with respect to the President, or though his custodians."