His decision was made with the agreement of the Home Affairs Committee and Boley Smillie, the States chief executive and head of the public service.
Mr De Carteret has led the prison since May 2020.
Deputy Governor Tracey Mahy will take over for the time being, as interim management arrangements are put in place.
‘Matters will be investigated fully and fairly and no one should draw any conclusion from the Prison Governor’s decision to temporarily step aside,’ said Mr Smillie. ‘I will provide an update once the investigation has concluded but will offer no further comment.’
A two-hour tour of Les Nicolles for deputies and media, which had been arranged for this coming Tuesday, in part to defuse concerns about its operation, was abruptly cancelled yesterday afternoon.
Les Nicolles has been in the spotlight in recent months, with significant criticism of prison management in the media which was accelerated following the deaths of two prisoners this year, one of which took place at the prison.
Both incidents have been formally referred to the Prison and Probation Ombudsman for independent investigation.
Just last week, a Freedom of Information request was submitted to Home Affairs about the alleged problems at the prison.
Questions included requests for the number of complaints alleging misconduct by officers in each of the past five years, with those dismissed shown separately from those upheld, and staff turnover since 2020, as well as information about prison officers suspended from duty.
It has also requested Home Affairs to confirm or deny claims of numerous complaints of misconduct made against prison officers last year by other members of States staff.
It is said that each complaint had been dismissed and several of the complainants have since quit their jobs.
A senior member of staff was jailed last year for sexual offences outside the prison, another officer was told to stay away from work after allegedly supplying drugs to an inmate with the possible involvement of accomplices, and Home Affairs was angered recently when the media were leaked claims of lax security while a convicted child sex offender was staying in hospital, which the committee rejected.
The prison’s most recent annual report stated that internal disciplinary offences had nearly trebled, while long-standing concerns remained about mental health services and accommodating children in an adult custodial facility, at a time of a rising number of inmates.
In the past few weeks the prison and the Home Affairs Committee have faced another round of claims of extensive and serious failings and calls for an independent review.
‘No workplace is immune to the failings of individuals.
‘However, the fact that prison officers have either been convicted of, or charged with, serious criminal offences within a short period makes people wonder about recruitment, vetting and supervision,’ said James Collings, a leading figure in the People’s Trust campaign group, in a letter to the Guernsey Press, published just last month.
‘These are not isolated incidents to be easily explained away, they form a pattern crying out for attention.’
Home Affairs president Marc Leadbeater has previously rejected claims of failure and wrongdoing at Les Nicolles ‘as wild speculation’ and criticised Deputy Rob Curgenven for ‘effectively endorsing them’ on social media.
He brushed aside political criticism, which he accepted as part of his role, but was unhappy with the effect on other individuals connected with the prison and their families.
‘None of them benefit from partial information, conjecture and insinuation being recycled in the public domain,’ he said.
Deputy Curgenven posted on the People’s Trust on Facebook yesterday afternoon, thanking Mr Smillie for not allowing issues to be ‘brushed under the carpet’.