According to Wikipedia "Persons of Interest" is a term used in the US and Canada.
Person of interest - Wikipedia
"Person of interest" is a term used by U.S. and Canadian law enforcement when identifying someone possibly involved in a criminal investigation who has not been arrested or formally accused of a crime. It has no legal meaning, but refers to someone in whom the police are "interested", either because the person is cooperating with the investigation, may have information that would assist the investigation, or possesses certain characteristics that merit further attention.[citation needed]
While terms such as suspect, target, and material witness have clear and sometimes formal definitions, person of interest remains undefined by the U.S. Department of Justice.[1] Unsub is a similar term which is short for "unknown subject" (used in the TV show Criminal Minds). Person of interest is sometimes used as a euphemism for suspect, and its careless use may encourage trials by media.