Hayley Jones, 33, pleaded guilty to misconduct in a public office over the fling with Jordan McSweeney, 31, between March 6 and April 7 last year at HMP Belmarsh.
She entered her plea to the charge during a hearing at Woolwich Crown Court on Thursday.
McSweeney, charged with encouraging or assisting the commission of an indictable offence, did not appear in court, either in person or by video link, and no plea was entered for the charge he faces.
Officers at HMP Long Lartin told the court that he was ‘having difficulty with walking’ and therefore could not make his way to the link room.
McSweeney killed 35-year-old Zara as she walked home from a night out in Ilford, east London, in the early hours of June 26, 2022.
He was handed a life sentence with a minimum term of 38 years at the Old Bailey in December 2022 after admitting sexually assaulting and murdering her.
In November 2023, he won a Court of Appeal bid to reduce the minimum term of his life sentence to 33 years.
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