HMP Chelmsford maths tutor admits misconduct after relationship with prisoner

A maths tutor at HMP Chelmsford has admitted misconduct in a public office after forming an inappropriate relationship with a serving prisoner.

Oksana Antanaitiene, 51, from Grays, appeared at Chelmsford Crown Court on Tuesday, September 22, where she admitted the offence.

Essex Police said an investigation into Antanaitiene was already under way when she was found inside a locked office at HMP Chelmsford with a serving male prisoner in August 2025.

Investigators subsequently established that she had communicated sexually with the prisoner through letters and telephone calls and had sent him sexually explicit images.

Explicit images and USB found in prisoner's cell

Antanaitiene worked at HMP Chelmsford as a maths tutor.

According to Essex Police, she had undergone two separate training sessions covering prison safety, corruption prevention and the requirements surrounding the delivery of teaching within a prison.

The prisoner's cell was searched on October 22, 2025.

Officers found explicit images of a woman during the search, while a USB device was discovered inside a dressing gown.

At an internal meeting the following day, Antanaitiene admitted that she had formed an inappropriate relationship with the prisoner and had sent photographs to him.

She also admitted supplying him with music and television files contained on a USB drive.

Police said further items of significance were subsequently recovered during searches of a vehicle and property connected to Antanaitiene.

Charged with misconduct in public office

Antanaitiene was charged with misconduct in a public office in July 2026.

She appeared at Chelmsford Crown Court on September 22 and admitted the offence.

She has been released on bail and is due to return to the same court for sentencing on October 28.

DC Matthew Parker, of Essex Police's Prison Investigations Team, said Antanaitiene had occupied a position of trust and was aware of the professional standards and boundaries required of her.

He said she had instead entered into an inappropriate relationship with a serving prisoner and continued the relationship through repeated contact, including the sharing of prohibited items and explicit material.

Police said her actions undermined the integrity of the prison system and had the potential to compromise safety and security within the establishment.

Source

The case and guilty plea were confirmed by Essex Police on September 23, 2026.