A prison nurse who had an affair with a convicted rapist at a top security jail has been locked up for three years.
Karen Cosford, 47, had sex with inmate Brian McBride, who was serving a life sentence at Wakefield Prison, during a relationship that lasted several months.
Three of her colleagues were also jailed for a total of more than four years for "covering up" the affair and "abusing their position of trust".
Cosford sent the prisoner intimate text messages on a smuggled mobile phone in which she told him he was "dead sexy" and that she loved him.
In a love letter, which was found hidden in a jar of sugar, she described him as her "knight in shining armour" and graphically described how she would have sex with him.
She also performed a sex act on McBride, who claimed he was hugely wealthy and promised her large sums of money, while on duty as two colleagues, Carolyn Falloon and Jacqueline Flynn, guarded his cell.
On another occasion Falloon caught her having sex with the inmate in the medical unit.
Cosford, of Normanton, West Yorkshire, who worked in the jail's medical centre, denied misconduct, claiming McBride raped her then intimidated her so she would not report it.
During a trial at Leeds Crown Court that lasted almost four weeks, she said he threatened to kill her and her family if she told anybody about their relationship.
But jurors rejected the claim after hearing how the prison nurse became inappropriately close to the inmate and struck up a sexual relationship.
The affair was exposed when McBride's cell was searched and he told Cosford's husband Darrie, a prison officer, that he had been having sex with his wife.
Cosford denied all charges but last week she was found guilty of misconduct by engaging in a sexual relationship with an inmate. She was also found guilty of failing to tell prison authorities that McBride had a mobile and bringing in top-ups on behalf of the prisoner.
Health care officer Carolyn Falloon, 50, of Wakefield, and nurse Jacqueline Flynn, 46, from Pontefract, were found guilty of failing to report the relationship and not reporting McBride's mobile phone. Falloon was also found guilty of supplying McBride with mobile top-ups.
Another of their colleagues, health care officer Kevin Wilson, 57, also of Normanton, earlier pleaded guilty to failing to notify authorities of Cosford's relationship, failing to tell authorities he had a mobile phone and supplying McBride with a Sim card.
Sentencing all four at Bradford Crown Court, Judge David Hatton QC said evidence suggested that "evil" McBride manipulated staff by claiming he had amassed great wealth and had links to the criminal underworld.
He was seen as a "privileged" and "protected" prisoner by some senior managers at the jail, the judge said.
But all the defendants should have known better and inevitably faced jail, he said.
"It's a sad business indeed when four people of mature years and previous good character, public servants who have devoted several years to their vocation, should find themselves to be sentenced for having abused their position of trust," he said.
"These acts and omissions each constituted a gross breach of security in a prison housing dangerous criminals.
"Each of you was aware at the time that your conduct constituted a significant breach of responsibility.
"I don't lose sight of the undoubted fact that each of you fell under the evil spell of the same unusually deceitful, manipulative prisoner Brian McBride but each of you were experienced and each of you had the power and duty to avoid that.
"The misconduct in this case is so serious that only a custodial sentence can be appropriate."
Judge Hatton said Cosford abused her position of trust and was motivated by perceived financial enhancement" after McBride boasted to her that he was a "man of means and influence".
He sentenced her to three years in jail.
Falloon and Flynn were placed in a "genuine dilemma" by their split loyalties but acted entirely inappropriately, the judge said as he jailed them for 21 months and 15 months respectively.
Wilson, who appeared as a witness during the trial, was granted credit for his guilty plea. But Judge Hatton said the evidence he gave was "unconvincing and in parts untruthful" and jailed him for 15 months.