A sheriff detective said my name came up within an investigation. He said I was not being arrested or was a person of interest. He had questions.

Normally the term "person of interest" means the same as what used to be referred to as a "suspect."  Often officers will not arrest or charge anyone until they first persuade the person to talk to them and answer questions (supposedly "voluntarily").  That's usually because if the person is not "in custody" - or not "under arrest" -- the officer is not required to read the person his Miranda rights (i.e., the right to remain silent and have anything he says used against).  It is not unusual for law enforcement officers to have enough information to make an arrest -- but hold off on the arrest until they try to get the person to talk to them.  Because after a person is read his Miranda rights, he usually understands how saying "anything" can be twisted and used against him.  So officers like to try to avoid letting a person know he is going to be arrested or charged until they get as much information as they can from the suspect (or "person of interest").   Sadly, sometimes even a person who was not a "person of interest" when the officer first questioned him becomes the suspect or "person of interest" after being questioned. Keep in mind, Miranda rights exist for a purpose -- including for those who are completely innocent.  Even law enforcement officers who occasionally get charged with committing a crime, often exercise their right to remain silent.  That should tell you something!