His conviction is on an indictment brought by the US Attorney's Office for the Southern District of New York in a criminal, not civil court as it would have been had the case been brought by the Securities and Exchange Commission.

U.S. Attorney Damian Williams said: “Trevor Milton lied to investors again and again — on social media, on television, on podcasts and in print."

The list of malfeasance is long (see the media release linked below) and includes

1. During [an] event and later, MILTON claimed that the prototype Nikola One “fully functions and works, which is really incredible.” In fact, the Nikola One prototype was never completed and never functioned. Rather, the prototype was wholly missing significant parts, including gears and motors, and the control system (i.e., the system that communicates the driver’s directions to the vehicle) and other significant systems were missing or incomplete.

2. In a filmed demonstration, the Nikola One was towed to the top of a hill, at which point the “driver” released the brakes, and the truck rolled down the hill until being brought to a stop in front of the stop sign.

(so, Google, how about that faked demo of Bard a few days ago ?)

3. (the illegality of this seems less than certain) "took advantage of the fact that Nikola went public by merging with a Special Purpose Acquisition Company or “SPAC,” rather than through a traditional IPO, by making many of his false and misleading claims during a period where he would have not been allowed to make public statements under rules that govern IPOs."

source: https://www.justice.gov/usao-sdny/pr/trevor-milton-sentenced-four-years…