The Chief Constable of Cleveland Police has resigned less than a year after taking over after 'serious' allegations emerged about his conduct.
Mike Veale, who arrived from Wiltshire Police in March last year, stood down with immediate affect.
Police and Crime Commissioner Barry Coppinger said an investigation is under way into allegations against Mr Veale.
He said: "My office has been made aware of allegations about the behaviour of Chief Constable Mike Veale.
"On Friday 18th January Mr Veale resigned with immediate effect.
"Due to the serious nature of the allegations, the matter has been referred to the Independent Office for Police Conduct.
"I am proud to oversee a police force where such allegations are always taken seriously.
"It is important that the appropriate processes are allowed to take effect and as a result, I am unable to comment further on this matter.
"Arrangements to secure an Interim Chief Constable are in the advanced stages and an announcement will be made later today. The current Cleveland Police leadership structure remains unchanged.
"As an organisation, Cleveland Police has undergone a comprehensive programme of transformation and improvement, which has been recognised by Her Majesty’s Inspectorate of Constabulary and Fire & Rescue Services.
"I am determined to ensure this progress will continue as I look to recruit a permanent replacement.
"I want to reassure our communities that the same dedicated and compassionate officers and staff, who bravely serve the people of Cleveland every day, will continue to work hard to keep you safe.”
An IOPC spokesperson said: “We can confirm that we have recently received a referral from Cleveland’s Police and Crime Commissioner concerning the conduct of Chief Constable Mike Veale.
“We are assessing the information we have received to decide what further action is required.”
Hartlepool MP Mike Hill said: “Hartlepool has been the focus of national news recently where it was exposed that our police were dangerously under resourced and crime was on the increase as a consequence.
"That national exposure led to an immediate meeting between me and Mike Veale and the beginning of a much tougher approach to visible policing and tackling crime in the town.
"He was certainly determined to refocus efforts on tackling crime head on and building a bigger presence on our streets.
"I make no judgement other than to say the new Interim Chief really does need to carry on with that determination to clamp down heavily on crime in our town."
Mr Houchen said he had 'no faith' in the appointment, raising concerns that the former Wiltshire police chief had been criticised for the handling of accusations of historical child sex abuse against former Prime Minister Sir Edward Heath and was being investigated for alleged misconduct relating to the case.
He was investigated over claims that he had deliberately damaged a phone belonging to the Wiltshire force in order to conceal contact relating to the investigation into the former Prime Minister, named Operation Conifer.
In September, the IOPC ruled that there was no evidence he had damaged the phone on purpose or with a motive to conceal evidence, but it said he had a misconduct case to answer because of his differing versions of events.
Mr Veale told colleagues that the phone had been dropped in a golf club car park and inadvertently run over by a vehicle.
He subsequently explained to IOPC investigators that the damage was in fact caused when he swung a club at his golf bag in frustration after playing a poor shot during a round in September 2017.
Mr Houchen also complained of comments attributed to Mr Veale regarding the treatment of sex offence complainants.
But Mr Coppinger hit back, referring to Mr Veale's 'outstanding' record.
Mr Houchen called on Mr Coppinger to resign today, taking to Twitter to say: "If ever there was a demonstration of how inept and useless PCC Barry Coppinger is, this is it.
"Our frontline officers and the public deserve better. Much better!
"Barry should resign immediately."
And he was highly critical of the Government's latest funding announcement, condemning the national formula which determines how much forces receive.