The mayor of Cambridgeshire and Peterborough has apologised after he was found to have breached the authority's code of conduct.
An investigation began almost two years ago after complaints were made about Nik Johnson's behaviour.
A panel asked him to make a written apology by the end of the week.
Mr Johnson said: "I regret having been the cause of upset and apologise unreservedly to those for whom I gave reason to complain."
The panel chose not to reveal details of the specific allegations Mr Johnson faced, but in a statement the Cambridgeshire and Peterborough Combined Authority said it had unanimously decided he breached the code in relation to "civility" and "disrepute".
A previous whistleblowing investigation, first made public in May 2022, alleged the mayor's then chief of staff, Nigel Pauley, had caused "stress and strain" to colleagues in the authority. Mr Johnson was accused of failing to take appropriate action over that behaviour.
Mr Pauley had helped Mr Johnson win a surprise election victory to become Cambridgeshire and Peterborough's first Labour mayor in May 2021.
He was made Mr Johnson's chief of staff, but left his post at the Combined Authority in February 2022. He previously denied any wrongdoing and told the BBC he had "no comment" on Tuesday's hearing, in which he played no part.
In a statement read at a committee meeting on Tuesday, Mr Johnson said: "I've had a lot of time to reflect on what happened in those early days and have long since realised that much of it needn't have.
"I'm sorry and I have wanted to say so for ages. I wish I knew then what I know now.
"I am a better person for everything that has gone on and, I would argue, a better mayor."
Mr Johnson, who took medical leave to have treatment for a heart condition, said it was "a year to the day that I was awaiting cardiac surgery in Papworth hospital".
He added that he was in "no doubt" that being a "relative, and perhaps surprise, newcomer" in the role of mayor, as well as "inheriting an organisation that I saw had been in desperate need of life support", contributed to his ill health.
"At the Combined Authority we must go above and beyond the standards expected of us, and any of us that fall short must be seen to take responsibility for their actions.
"I am sorry. I do apologise and I can only hope that through my words today and my actions since those difficult times two years ago, those to whom I am apologising can at some point accept that I mean it," he concluded.
The Combined Authority asked a firm of independent solicitors to investigate the complaints about Mr Johnson. Last month, their report was passed to the Authority's monitoring officer, who decided it should be referred to a panel.
The panel, made up of one Labour, one Conservative and one Liberal Democrat councillor, as well as a chair who is not a councillor, determined that Mr Johnson had breached the authority's code of conduct.
John Pye, the panel's chair, said all its decisions were made unanimously.
He said the panel would "invite" the mayor to provide a written apology to the Authority and to "consult with the monitoring officer about the appropriateness of providing a written apology directly to one or more of the complainants".
The panel also said it would ask the mayor "for an undertaking not to repeat this behaviour" and agree appropriate "development and training" within the next six months, dealing with "HR practice when acting in a senior member role".
It recommended that the Combined Authority "reviews and improves" its induction process for new mayors.
Chief executive Rob Bridge said: "I want to take this opportunity to apologise to those impacted by this process. The period covered by the investigation was a very difficult time for the Authority and anyone who was involved, but I am confident that the Authority has learned many lessons from that period and is on a much more stable footing.
"This investigation was an important and necessary process, which has been undertaken with impartiality, professionalism and thoroughness."