An officer at a top security prison was told she will be jailed after she admitted having an affair behind bars with the notorious criminal Curtis "Cocky" Warren.
Stephanie Smithwhite, 40, was an officer at HMP Frankland near Durham where the gangster - once named in the Sunday Times Rich List - was serving time.
She appeared before Durham Crown Court to admit two counts of misconduct in a public office.
The first count related to their sexual relationship, said to have lasted between June and December 2018.
The second count related to her not reporting that she knew he had access to a smuggled phone.
It was understood this tiny handset was a so-called "prison phone" little bigger than a £2 coin.
Smithwhite, who is from Boldon Colliery, South Tyneside, will be sentenced on February 7, after the Probation Service has completed a report.
She was granted bail in the meantime.
Judge Jonathan Carroll said: "You have pleaded guilty to these two serious offences, you understand, I am certain, how serious they are.
"The overwhelming likelihood is this will be followed by an immediate custodial sentence.
"Your background should be fully investigated before I pass sentence, you should understand the purpose is to assist me with the length rather than the type of disposal."
Earlier in the hearing, the judge said: "The level of the breach of trust in a case like this is profound."
Warren, 57, is a Liverpool-born gangster who became an international drug trafficker worth tens of millions of pounds.
He moved to the Netherlands in the 1990s and was jailed there after officers raided his villa and found a huge haul of drugs and weapons.
He was convicted of manslaughter following a prison yard fight with a Turkish inmate.
Just weeks after his release he was arrested in Jersey for a major drug smuggling plot and was told in 2013 he faced another 10 years in jail if he did not abide by a £198m confiscation order.
