A prison officer is to be charged with manslaughter following the death of an inmate at HMP Woodhill, Milton Keynes.
Joseph Travers will be charged with gross negligence manslaughter in relation to the death of Ryan Harvey and misconduct in public office.
Mr Harvey, 23, was found hanged in his cell at the Buckinghamshire jail on 8 May 2015.
Mr Travers is thought to be the first prison officer to be charged with manslaughter after a prisoner death.
The Crown Prosecution Service said: "Following careful consideration of all the evidence provided to us by the police it has been decided that Joseph Travers should be charged."
Mr Harvey was one of five prisoners found hanging in their cells in HMP Woodhill in 2015.
The prison had the worst record for suspected suicides in all of England and Wales that year.
Mr Travers will appear before Westminster Magistrates' Court on 20 April.
HMP Woodhill, a Category A prison, opened in 1992 and can hold 819 inmates.