The fact that you show up on a surveillance cam at the time and place of the incident is called, “evidence”. If someone is collecting evidence and calling you a suspect, (or the trendy term with identical meaning, “person of interest”) you damned well better have a lawyer.
The terms can be interchangeable depending on how broad you’re willing to go. If the cops have zero idea who did something and they have you on video over the last few hours, then technically you could be labeled as a ‘suspect’ until you are eliminated as one. Cops use ‘person of interest’ because it doens’t sound a s bad. And usually a five minute conversation will totally exonerate many of these people.
They also took this guy’s car to search for evidence and searched his apartment last weekend. Guilty or innocent, he most definitely needs a lawyer.