"Person of interest" is a term used by law enforcement in the United States, Canada, and other countries when identifying someone possibly involved in a criminal investigation who has not been arrested or formally accused of a crime.
[2] 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.
According to Eric Lichtbau in The New York Times: The term has an ugly history; in the 1960s American law enforcement officials began creating secret dossiers on Vietnam War protesters, civil rights leaders and other persons of interest...The vaguely sinister term has been applied to targets of terrorism investigations, the chief suspect in the murder of the Baylor basketball player Patrick Dennehy and Steven J. Hatfill, the scientist who has figured prominently in the investigation into the 2001 anthrax attacks...Attorney General John Ashcroft is often credited with popularizing the person-of-interest label, having used it [in 2002] to describe Dr.
[5]The use of the term became widely critiqued when United States Attorney General John Ashcroft used it in a press conference when asked if Dr. Steven J. Hatfill was a suspect in the 2001 anthrax attacks case.
Senator Chuck Grassley, Republican of Iowa, wrote to the Attorney General for clarification of the unfamiliar phrase in September 2002.
… The department did not intend to cause any harm to Hatfill when it described him as a person of interest, Assistant Attorney General Daniel Bryant said in one of the letters.
"I also appreciate the department's candidness that the action regarding Mr. Hatfill and his employment is unprecedented," Grassley said in a statement, and that "there is no … formal definition for the term 'person of interest.'"