Today, he became the first former President to be indicted of a crime. This indictment is a long time in coming. It relates to the misuse of campaign funds (which he used to hush up an affair he had with a porn star) during the 2016 election year. During his time as President, he actively suppressed the investigation which picked up again after he was voted out of office. Despite his protestations, this is not a "witch hunt." This is a criminal investigation that led to a grand jury unanimously voting for his indictment based on the evidence presented to them.
It will only be the first of the indictments that he is likely to face in the near future. In fact, this is probably the crime which holds the lowest (but still quite significant) penalty of the trials that he will see. This will likely be a bad year for him, as there is a good chance that he will also gain a new first, as the first President convicted for a crime.