The police watchdog has said it was "completely unacceptable" for a police finance officer to quit ahead of a disciplinary hearing.
Ann Hall was suspended following an allegation of potential gross misconduct relating to the misuse of public funds.
She was allowed to resign by Cleveland Police, despite a disciplinary hearing by the force being due to happen this month.
The decision has been criticised by the Independent Police Complaints Commission which has been carrying out a separate investigation into her conduct.
It has now vowed to go on with its own inquiry into an allegation that unauthorised payments amounting to thousands of pounds were made to an executive coaching company, and says its findings will still be published.
"I am very mindful that the public are extremely concerned when officers and staff resign or retire while under investigation, thereby escaping a misconduct sanction.
"I find it completely unacceptable that individuals take this option rather than face up to the case against them.
"The IPCC cannot prevent this happening and that is frustrating.
"The misconduct process should be seen through to conclusion - if it is not it will inevitably leave unanswered questions and erode public confidence.
"While we cannot bring this case to a misconduct conclusion now, I believe it is in the public interest for our investigation to continue and we will publish the evidence and our conclusions, so that the public can judge the actions of Ann Hall for themselves."
A senior civilian officer at Cleveland Police has resigned ahead of a disciplinary hearing for gross misconduct, her employers said.
Ann Hall was suspended following an allegation of potential gross misconduct relating to the misuse of public funds between June 2010 and October 2011.
The disciplinary hearing was due to take place this month.
The new Chief Constable appointed an independent investigator to look into matters at Cleveland Police and it was found there was a potential case for gross misconduct.
The Independent Police Complaints Commission was investigating an allegation of potential misconduct relating to the misuse of public funds between July 2010 and October 2011.
She was suspended for this matter in February 2013 and the IPCC investigation continues.
"Three Chief Officers have now left the Force; two have been dismissed and one has resigned. This brings to an end the conduct issues raised into those previously at the helm of the organisation.
"I was recently appointed as permanent Chief Constable, there is a new Deputy Chief Constable in place and around 60% of the current leadership team are new in post.
"Cleveland Police has considered the issues raised by the actions of the previous top team.
"We have and will continue to amend practices, policies and procedures to prevent such things happening again and we will ensure that our police officers and police support staff receive the good and ethical leadership they deserve as they do their difficult and challenging work.
"I would ask that we are now given the opportunity to put these misconduct issues behind us so we can get on with our job of keeping the public safe and protecting them from harm."
– Jacqui Cheer, Chief Constable of Cleveland Police