A former Surrey Police officer has admitted selling information, including details about footballer John Terry's mother, to the Sun newspaper.
Alan Tierney, 40, pleaded guilty at the Old Bailey to two offences of misconduct in a public office.
Ex-prison worker Richard Trunkfield, 31, and an ex-policeman also pleaded guilty to misconduct in public office.
And a fourth person, a public official, also admitted conspiring to commit misconduct in public office.
Tierney and Trunkfield had been charged as part of Operation Elveden into corrupt payments.
The operation is being run alongside Scotland Yard's Operation Weeting, which is looking into phone hacking.
Tierney, from Hayling Island in Hampshire, passed on details about two stories in 2009, the court heard.
The first was about the mother of Chelsea captain John Terry, who had been cautioned for shoplifting. The other was about Rolling Stone Ronnie Wood, who was cautioned for assault after an incident with his then girlfriend.
The former officer admitted one count of misconduct in a public office between 26 March and 3 April 2009, and the second between 2-7 December 2009.
Tierney was released on bail and will be sentenced on 27 March. Mr Justice Fulford warned him that "all options remain open".
He is the second police officer to be convicted under Operation Elveden, following the case of ex-counter-terrorism detective April Casburn.
Trunkfield, from Moulton in Northamptonshire - a former prison operational support officer at HMP Woodhill, in Milton Keynes, Buckinghamshire - admitted leaking information about a high-profile prisoner to the tabloid.
He was paid £3,350, the court heard.
Trunkfield pleaded guilty to misconduct in a public office between 2 March and 30 April 2010. He will be sentenced at a later date.
The second police officer and the public official could not be named for legal reasons.
Coulson in court
Ex-News International chief executive Rebekah Brooks, 44, from Churchill, Oxfordshire, also appeared at the Old Bailey on Friday to face charges in relation to a separate case. Her case was adjourned until April.
John Kay, the Sun's chief reporter, also appeared at the Old Bailey and pleaded not guilty to an offence of conspiracy to commit misconduct in a public office.
Mr Kay, 69, from north-west London, pleaded not guilty.
In a separate case, the prime minister's former chief spokesman, Andy Coulson, 45, from Kent, appeared at the Old Bailey facing charges over an alleged conspiracy to bribe public officials for information.
The former News of the World editor is accused, along with ex-NoW royal correspondent Clive Goodman, 55, from Surrey, of requesting and authorising payments to public officials in exchange for information, including a royal phone directory known as the Green Book.
The pair face two counts of conspiracy to commit misconduct in a public office - one between 31 August 2002 and 31 January 2003, and the other between 31 January and 3 June 2005.
Their case was adjourned until next month.