No action will be taken against any police officers who investigated the force's medical advisor Hugh O'Neill - who was later jailed for a series of sex attacks.

Norfolk Police today published the results of an Essex Police inquiry into its handling of sexual abuse allegations made by police officers assaulted by O'Neill.

He was the force medical advisor between 1991 and 2003, and used his position to sexually assault a number of female officers.

He pleaded guilty to 13 offences of indecent assault and was sentenced in April 2016 to three years' imprisonment. The sentence was added to a 12-year prison sentence he received in January 2015 for offences of rape and sexual assault, unconnected to his police role.

In 1993 and 2002, female officers had made allegations of sexual assault against O'Neill, but after an investigation no criminal charges were brought.

In 2014, the then Chief Constable made a referral to the Independent Police Complaints Commission (IPCC) concerning Norfolk Constabulary's handling of the 1993/2002 allegations.

The local investigation by Essex Police Serious Crime Directorate has today been published.

MORE: Downfall of a police doctor: Questions remain as Norfolk GP Hugh O'Neill is jailed for another three yearsIn relation to the 1993 investigation, two retired officers were looked at for criminal and misconduct offences:

? The Crown Prosecution Service found insufficient evidence for a criminal prosecution.

? Deputy Chief Constable Nick Dean determined there could be a case to answer for gross misconduct. However, as the officers are retired, no further action could be taken.

In relation to the 2002/3 investigation, Essex officers looked into the conduct of two retired officers, one serving officer and one police staff member:

? DCC Dean said the two retired officers had a possible case to answer for misconduct, however as the officers are retired, no further action could be taken.

? The police staff member and serving police officer had no case to answer.

Norfolk Chief Constable Simon Bailey said: 'On behalf of the victims it was vital that we examined and assessed the organisation's response to these earlier allegations, notwithstanding the fact that they would all recognise that the way in which the police respond to and deal with allegations such as these has changed considerably since the investigations took place.

'I am acutely aware of the impact this case has had on the affected officers. I'm sorry that during the recent criminal investigation and the Essex inquiry, those involved had to relive the experiences which they endured at the hands of O'Neill.

'I am immensely proud of the way in which they have conducted themselves throughout and I will be speaking to them personally about the outcome of the investigation.'

Hugh Blaise O'Neill, 63, formerlly of Tasburgh, was Norfolk Police's medical adviser between 1991 and 2003 and had been a trusted and respected member of the policing community.

But he repeatedly breached that position of trust, using it as a smokescreen to sexually abuse police staff.