Private investigator

For the TV series, see Private Investigator (TV series).
"Private investigation" redirects here. For the song, see Private Investigations (song). For the album, see Private Investigations (album).
"Private Detective" redirects here. For the film, see Private Detective (film).
Private detectives can perform surveillance work on behalf of individuals
Sherlock Holmes, the world's most famous fictional private investigator

A private investigator (often abbreviated to PI and informally called a private eye), a private detective, or inquiry agent is a person who can be hired by individuals or groups to undertake investigatory law services. Private investigators often work for attorneys in civil and criminal cases.