There are tactical reasons for this which is why the POI term is used universally now. Labeling a person a “suspect” too early can be used against the state at trial.
Facts aren’t welcome here.
Nope. It cannot and POI has zero legal definition according to the courts and DOJ. None, zip, nada.
The minute a reasonable person would form the idea that this person had something to do with it, the term is “suspect”. That allows the police to further investigate. That investigation can find nothing, exonerate, or find evidence that elevates things to charges being filed.
And it is not universally used except by PIOs, the media, FBI twits, hit TV shows, and housewives. No professional uses it because there is no status where you can be a person of interest without being a suspect.
The fact that they are interested in you MEANS you are a suspect. Otherwise they would seek him as a witness or possible witness.