To turn state's evidence is when an accused

Suspect

In the parlance of criminal justice, a suspect is a known person suspected of committing a crime.Police and reporters often incorrectly use the word suspect when referring to the...

 or convicted criminal testifies as a witness for the state against his associates or accomplices. Turning state's evidence is occasionally a result of a change of heart or feelings of guilt, but more often is done in response to a generous offer from the prosecution, such as a reduced sentence or a favorable location for serving time. In particularly high-profile or dangerous cases such as organized crime

Organized crime

Organized crime or criminal organizations are transnational, national, or local groupings of highly centralized enterprises run by criminals for the purpose of engaging in illegal activity, most commonly for monetary profit. Some criminal organizations, such as terrorist organizations, are...

 trials including other federal crime

Federal crime

In the United States, a federal crime or federal offense is a crime that is made illegal by U.S. federal legislation. In the United States, criminal law and prosecution happen at both the federal and the state levels; thus a “federal crime” is one that is prosecuted under federal criminal law, and...

s trials, the witness may be offered immunity from prosecution even if he has committed serious crimes himself, up to and including murder. The state may also offer the witness a place in the witness protection program, giving them a new identity so they need not fear retaliation from their former accomplices.

In the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, the term is to turn Queen's or King's Evidence, both of which still mean the same thing.

Famous cases

Witness	Testified against	Charge(s)	Received for testimony
Salvatore "Sammy The Bull" Gravano Sammy Gravano Salvatore "Sammy the Bull" Gravano is a former underboss of the Gambino crime family. He is known as the man who helped bring down John Gotti, the family's boss, by agreeing to become a Federal Bureau of Investigation informant and turn state's evidence.Originally a mobster for the Colombo crime... , mob hit man	John Gotti John Gotti John Joseph Gotti, Jr was an American mobster who became the Boss of the Gambino crime family in New York City. Gotti grew up in poverty. He and his brothers turned to a life of crime at an early age...	racketeering
Frank "Curly" Lino of the Bonanno crime family Bonanno crime family The Bonanno crime family is one of the "Five Families" that dominates organized crime activities in New York City, United States, within the nationwide criminal phenomenon known as the Mafia ....	Ron Filocomo	murder of Sonny Black Napolitano Sonny Black Napolitano Dominick Napolitano , also known as Sonny Black, was an American Mafia caporegime in the Bonanno crime family. He is well known for allowing FBI agent Joseph "Donnie Brasco" Pistone to become an associate in his crew and nearly getting him made.-Biography:Napolitano's grandparents were immigrants...	?
"Easy Eddie" O'Hare Edward J. O'Hare Edward Joseph O'Hare , aka "Easy Eddie" , was a lawyer in St. Louis and later in Chicago, where he began working with Al Capone, and later helped federal prosecutors convict Capone of tax evasion. In 1939, a week before Capone was released from Alcatraz, O'Hare was shot to death while driving... , mobster	Al Capone Al Capone Alphonse Gabriel "Al" Capone was an American gangster who led a Prohibition-era crime syndicate. The Chicago Outfit, which subsequently became known as the "Capones", was dedicated to smuggling and bootlegging liquor, and other illegal activities such as prostitution, in Chicago from the early...	tax evasion	According to some sources, his son Butch's admission to the U.S. Naval Academy in Annapolis
Harry Orchard, mass murderer	William "Big Bill" Haywood	assassination of former governor of Idaho Frank Steunenberg Frank Steunenberg Frank Steunenberg was the fourth Governor of the State of Idaho, serving from 1897 until 1901. He is perhaps best known for his 1905 assassination by one-time union member Harry Orchard, who was also a paid informant for the Cripple Creek Mine Owners' Association...	?
Jimmy Leibrant, accessory to murder	Karla Faye Tucker Karla Faye Tucker Karla Faye Tucker was convicted of murder in Texas in 1984 and put to death in 1998. She was the first woman to be executed in the United States since 1984, and the first in Texas since 1863...	murder of Jerry Lynn Dean	full immunity
James Jordan James Jordan -Sports:*James Jordan , English first-class cricketer*Jimmy Jordan , American Major League Baseball player*Jim Jordan , American guard-Arts:*Jim Jordan , American radio comedy performer... , Klansman and accessory to murder	18 other Klansmen including Neshoba County deputy Cecil Price Cecil Price Cecil Ray Price was linked to the murders of three civil rights workers in 1964. At the time of the murders, he was 26 years old and a deputy sheriff in Neshoba County, Mississippi...	murder of three civil rights workers Mississippi civil rights worker murders The Mississippi civil rights workers murders involved the lynching of three political activists in Neshoba County, Mississippi on June 21, 1964, during the American Civil Rights Movement....	full immunity, $3500 and help in relocating himself and his family
Christie's Christie's Christie's is an art business and a fine arts auction house.- History :The official company literature states that founder James Christie conducted the first sale in London, England, on 5 December 1766, and the earliest auction catalogue the company retains is from December 1766...  auction house	Sotheby's Sotheby's Sotheby's is the world's fourth oldest auction house in continuous operation.-History:The oldest auction house in operation is the Stockholms Auktionsverk founded in 1674, the second oldest is Göteborgs Auktionsverk founded in 1681 and third oldest being founded in 1731, all Swedish...	commission rate-fixing	protection from criminal prosecution (for the business—however the former chairmen of both companies were indicted)
Linda Kasabian Linda Kasabian Linda Kasabian is a former member of Charles Manson's "family". She was the key witness in District Attorney Vincent Bugliosi's prosecution of Manson and his followers for the Tate-LaBianca murders, one of the highest-profile murder trials in American history.-Early life:Born as Linda Darlene... , driver of the getaway car in the Tate/LaBianca murders	Charles Manson Charles Manson Charles Milles Manson is an American criminal who led what became known as the Manson Family, a quasi-commune that arose in California in the late 1960s. He was found guilty of conspiracy to commit the Tate/LaBianca murders carried out by members of the group at his instruction...  and other members of the Manson Family	multiple murders	immunity from prosecution
James "Dick" Liddil Dick Liddil James Andrew "Dick" Liddil was an American outlaw who was one of the last surviving members of the James-Younger Gang... , bank robber, murderer and member of the James-Younger gang James-Younger gang The James-Younger Gang was a notable 19th-century gang of American outlaws that included Jesse James.The gang was centered in the state of Missouri. Membership fluctuated from robbery to robbery, as the outlaws' raids were usually separated by many months...	Jesse James Jesse James Jesse Woodson James was an American outlaw, gang leader, bank robber, train robber, and murderer from the state of Missouri and the most famous member of the James-Younger Gang. He also faked his own death and was known as J.M James. Already a celebrity when he was alive, he became a legendary...	robbery, murder	immunity from prosecution
Daniel Tucker Bassham, member of the James-Younger gang	William "Whiskey Head" Ryan, member of the James-Younger gang	robbery, murder	10-yr sentence commuted, released from Missouri State Penitentiary
Wayne DuMond Wayne DuMond Wayne Eugene DuMond was an American criminal convicted of murder and rape. He was born in De Witt, Arkansas, and is buried in the Mt. Pleasant Cemetery of Ethel, Arkansas.DuMond had six children and three wives... , rapist	various acquaintances	murder	pardoned by Gov. Mike Huckabee
John Dean John Dean John Wesley Dean III is an American lawyer who served as White House Counsel to United States President Richard Nixon from July 1970 until April 1973. In this position, he became deeply involved in events leading up to the Watergate burglaries and the subsequent Watergate scandal cover-up...	Richard Nixon Richard Nixon Richard Milhous Nixon was the 37th President of the United States, serving from 1969 to 1974. The only president to resign the office, Nixon had previously served as a US representative and senator from California and as the 36th Vice President of the United States from 1953 to 1961 under...  and others	Watergate	very light sentence, "jail" time served in a safe house at Fort Holabird
Robert Rozier, murderer and cult member	Hulon Mitchell, Jr. (Yahweh ben Yahweh Yahweh ben Yahweh Yahweh ben Yahweh was the adopted name of Hulon Mitchell, Jr. , founder and leader of the Nation of Yahweh, a black supremacist new religious movement founded in 1979.... ), cult leader	murder, racketeering	reduced sentence
David Greenglass David Greenglass David Greenglass was an atomic spy for the Soviet Union who worked in the Manhattan project. He was the brother of Ethel Rosenberg.-Biography:... , spy, passed information about the Manhattan Project Manhattan Project The Manhattan Project was a research and development program, led by the United States with participation from the United Kingdom and Canada, that produced the first atomic bomb during World War II. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the US Army...  to...	...Julius and Ethel Rosenberg Julius and Ethel Rosenberg Ethel Greenglass Rosenberg and Julius Rosenberg were American communists who were convicted and executed in 1953 for conspiracy to commit espionage during a time of war. The charges related to their passing information about the atomic bomb to the Soviet Union...	treason, spying	immunity for his wife, who served as his courier
Henry Hill Henry Hill (mobster) Henry Hill is a former American mobster, Lucchese crime family associate, and FBI informant whose life story was documented in the book Wiseguy, written by crime reporter Nicholas Pileggi, and in the 1990 Martin Scorsese film, Goodfellas, in which Hill was played by Ray Liotta.-Early life:Henry... , mobster	Paul Vario Paul Vario Paul Vario was a caporegime of a crew in the Lucchese crime family. In the 1970s Vario held the position of consigliere in the family but later resigned. In 1980, longtime associate Henry Hill became a government witness and testified against Vario and members of his crew...  and Jimmy Burke	racketeering charges	immunity from prosecution and witness protection Witness protection Witness protection is protection of a threatened witness or any person involved in the justice system, including defendants and other clients, before, during and after a trial, usually by police...  for Hill and his family
Abe "Kid Twist" Reles Abe Reles Abe "Kid Twist" Reles was a New York mobster who was widely considered the most feared hit man for Murder, Inc., the enforcement contractor for the National Crime Syndicate. Reles later turned government witness and sent several members of Murder, Inc... , Mafia hit man	Louis "Lepke" Buchalter Louis Buchalter Louis "Lepke" Buchalter was a Jewish American mobster and head of the Mafia hit squad Murder, Inc. during the 1930s. After Dutch Schultz' request of the Mafia Commission for permission to kill his enemy, U.S. Attorney Thomas Dewey, the Commission decided to kill Schultz in order to prevent the hit... , members of Murder, Inc. Murder, Inc. Murder, Inc. was the name given by the press to organized crime groups in the 1920s through the 1940s that resulted in hundreds of murders on behalf of the American Mafia and Jewish Mafia groups who together formed the early organized crime groups in New York and...	murder	no death penalty
William Hare, the West Port murders West Port murders The Burke and Hare murders were serial murders perpetrated in Edinburgh, Scotland, from November 1827 to October 31, 1828. The killings were attributed to Irish immigrants William Burke and William Hare, who sold the corpses of their 17 victims to provide material for dissection...  in Edinburgh Edinburgh Edinburgh is the capital city of Scotland, the second largest city in Scotland, and the eighth most populous in the United Kingdom. The City of Edinburgh Council governs one of Scotland's 32 local government council areas. The council area includes urban Edinburgh and a rural area... , Scotland Scotland Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...	William Burke	murder	immunity from prosecution
Joseph Massino, Bonanno crime boss			no death penalty