By Tony O’Reilly-
A maths tutor who was trusted to educate prisoners at HMP Chelmsford has admitted misconduct in public office after forming an inappropriate relationship with a serving inmate, communicating with him sexually and sending him explicit photographs, in a case that has raised fresh questions about security and staff boundaries inside one of Essex’s most closely scrutinised prisons.
Oksana Antanaitiene, 51,(pictured) had already come under investigation when she was discovered inside a locked office at HMP Chelmsford with the male prisoner in August 2025.
Essex Police subsequently established that the relationship had continued through letters and telephone calls and that she had sent sexually explicit images of herself to the inmate. She had also supplied him with music and television files on a USB device.
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The case has now moved decisively beyond the investigation stage. Antanaitiene was charged with misconduct in public office in July 2026 and appeared before Chelmsford Crown Court on September 22, where she admitted the offence. She was released on bail ahead of sentencing at the same court on October 28.
The investigation began to reveal the extent of the relationship after the prisoner’s cell was searched on October 22, 2025. Officers found explicit images of a woman and discovered a USB device inside a dressing gown.
The following day, during an internal meeting, Antanaitiene admitted that she had formed the inappropriate relationship and had sent the photographs. She also acknowledged giving the prisoner music and television files contained on the USB.
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Police subsequently searched a vehicle and property connected to Antanaitiene and recovered what Essex Police described as “other items of significance”. The force has not publicly detailed those additional items, meaning it would be inappropriate to speculate about exactly what they were or what they may have been intended to facilitate.
The seriousness of her conduct from a prison-security perspective is that Antanaitiene was not unaware of the rules governing her position. Essex Police said she had undergone two separate training sessions covering prison safety, corruption prevention and teaching within a prison environment.
Detective Constable Matthew Parker, of Essex Police’s Prison Investigations Team, said Antanaitiene occupied a position of trust and was fully aware of the professional standards and boundaries expected of her.
He said her decision to enter into the relationship and continue communicating with the prisoner through prohibited material had undermined the integrity of the prison system and had the potential to compromise the safety and security of the establishment.
The wider significance of the case becomes clearer when it is placed against national figures. Ministry of Justice data disclosed to Parliament in April 2026 recorded 22 prisoners in 2025 as being involved in proven cases where a member of prison staff was convicted of misconduct in public office.
The corresponding figure was 10 in 2024, 17 in 2023, five in 2022, five in 2021 and none in 2020. The Government cautions that the figures come from administrative systems and may contain data-entry or processing errors
Those figures relate to prisoners recorded as being involved in proven cases in which a member of prison staff was convicted of misconduct in public office, and the category can encompass wider forms of inappropriate relationships and corruption. Nevertheless, they demonstrate that the problem is not confined to one prison or one unusual case.
There is additional evidence of the scale of the problem from earlier Ministry of Justice data. Between 2009-10 and 2019-20, the number of prison staff dismissed following conduct and disciplinary action for inappropriate relationships with prisoners or former prisoners ranged from three to 15 a year. Eight staff were dismissed in 2019-20 alone.
A separate parliamentary answer revealed that 64 prison staff in England and Wales were subject to disciplinary action for inappropriate relationships with prisoners between mid-2013 and mid-2018.
Security breaches were a much larger category, but inappropriate relationships were identified as a distinct disciplinary problem. The reason prison authorities treat such relationships as a security concern rather than merely an issue of personal conduct is that an inmate-staff relationship can create opportunities for manipulation, coercion, bribery, trafficking of prohibited items and the passing of information.
A staff member who becomes personally involved with a prisoner can potentially be pressured into breaking other rules, while the prisoner may acquire influence over someone with legitimate access to restricted areas, information, equipment or other prisoners.
That risk is particularly relevant to the Chelmsford case because the relationship allegedly extended beyond personal communications. The police investigation found evidence of sexually explicit communications as well as the transfer of a USB containing music and television files.
While the available evidence does not establish that Antanaitiene facilitated wider criminal activity, the movement of unauthorised material across the prison boundary illustrates why apparently personal relationships can become security matters.
And HMP Chelmsford has already experienced other cases involving a member of teaching staff and a prisoner in the past. Melissa Murphy, formerly Melissa O’Brien, was sentenced in January 2026 to eight months in prison and a 12-month supervision order after admitting misconduct in public office over an inappropriate relationship with an inmate.
She had worked at HMP Chelmsford for four years and had met the prisoner in 2023. Investigators discovered letters between the pair, while a photograph of the prisoner was found beside Murphy’s bed at her home.
That earlier case contained its own striking security breach. Another member of prison staff attempted to enter a classroom where Murphy and the prisoner were alone and found the door locked from the inside, with Murphy’s keys removed from her person. Her role required her to keep those keys attached to her because prisoners potentially accessing them could create an escape risk.
The proximity of the two cases makes Chelmsford an especially uncomfortable backdrop for Antanaitiene’s conviction. It does not establish that the two incidents were connected, nor does it prove that the prison has a systemic failure, but it does demonstrate that inappropriate relationships between staff and prisoners have occurred at the same establishment more than once within a relatively short period.
The prison itself has undergone considerable scrutiny in recent years. An unannounced inspection by HM Inspectorate of Prisons in early 2024 found that Chelmsford had improved from the crisis conditions identified in 2021, when inspectors issued an Urgent Notification.
Violence had reduced, staff had improved efforts to control contraband and participation in education, training and work had increased. However, inspectors still rated safety and purposeful activity as “not sufficiently good”, while use of force remained high and important problems persisted around prisoner support and preparation for release.
Education is supposed to be one of the mechanisms through which prisons prepare people for life after custody. Tutors are therefore placed in a position that requires both trust and regular interaction with prisoners.
The overwhelming majority of prison staff carry out that role without becoming involved in misconduct, but cases such as Antanaitiene’s show why the boundaries have to be exceptionally clear.
The Government’s definition of an inappropriate relationship is any relationship that compromises a staff member’s ability to perform their duties appropriately. The Ministry of Justice has also confirmed that sexual relationships with prisoners fall within its disciplinary framework, while broader inappropriate relationships are separately recorded.
Antanaitiene’s guilty remains on bail until her sentencing hearing on October 28, when the court will determine the punishment for the offence.
The much bigger question hanging over HMP Chelmsford and the wider prison estate is in relation to how effectively can authorities prevent staff who have extensive access to prisoners from crossing professional boundaries before a relationship becomes a security problem?
The answer is unlikely to lie in one additional rule or training session. Antanaitiene had already received training on prison safety and corruption prevention, yet police say she nevertheless entered into a relationship involving sexual communications, explicit photographs and the transfer of prohibited material. The earlier Murphy case demonstrates that training alone cannot eliminate the risk.
The latest shocking case demonstrates why prison authorities treat inappropriate staff-prisoner relationships as matters of institutional security rather than private affairs.
Once personal relationships cross the prison boundary, the potential consequences can extend far beyond the two people involved, affecting staff integrity, prisoner safety, the movement of prohibited material and public confidence in the prison system. This guilty plea is another serious chapter in a prison that has spent years trying to demonstrate that it can overcome its troubled past.