Actually, there is nothing in the Constitution that would prohibit a sitting President from being arrested, by any law enforcement officer.
The problem is, the President could then issue himself a prompt “pardon” and things would get messy.
Better to have the cabinet act, if it needed to be done quickly.
That's right. I believe at least one president (Pierce) haa been arrested. This was for what one might describe as pedestrian crime - literally - hit someone with his horse or carriage. But the charge was later dropped - I think.
Arresting a person who happens to be the President is one matter. Removing he/she from office, is another matter altogether. That can only be accomplished by Congress.