I write this in the spirit of transparency, because in the wake of a scandal at City Hall, I think San Franciscans are entitled to hear directly from their Mayor. And also, quite frankly, to dispel some unfortunate rumors that have already begun to circulate.

Mohammed Nuru and I have been close personal friends for more than 20 years. We dated for a brief time, two decades ago, long before I ever ran for office. Nevertheless, he, and his now-adult daughters, have remained close friends for all those years.

And so it was with a profound sense of shock, sadness, disappointment and anger that I learned of the federal charges against Mohammed announced two weeks ago.

From the perspective of serving as your Mayor, I was furious. The allegations against Mohammed and his co-defendants, if proved, represent a betrayal of the public trust that cuts to the core of our mission, and our duty, as public servants. This could weigh down the hardworking women and men of not only the Public Works Department, but the City workforce as a whole. We endeavor to earn the public trust, work hard and achieve results for our City, but scandals like this one cut away at the public’s faith in our departments.

From the perspective of a close personal friend, I was confused and heartbroken. If the charges are true, I can only wonder how could someone give up so much, for seemingly so little, endanger one’s hard-earned reputation and livelihood, and upend the lives of family, friends, colleagues and the citizens he served?

It was, and remains, shocking.

To be clear: I never asked Mohammed Nuru to do anything improper, and he never asked me to do anything improper. I was not aware of the schemes alleged by the FBI until shortly before they became public, and when I was informed, I immediately reported the information to our City Attorney.

When he was arrested, Mohammed was placed on leave by his supervisor. I immediately called for the City Attorney and Controller to conduct an independent investigation into the charges and the impacted departments, and issued an Executive Directive calling on City employees to be transparent and prioritize cooperation with the investigation.

Shortly after he was arrested, some local officials and many in the public called for his immediate firing. While I understand that call, it’s imperative that we respect all the laws and procedures pertaining to a public employee’s termination. Before this process had been completed, however, he submitted his resignation.

Now, we will all have to let the justice system take its course.

For my part, I will do my job — which includes supporting the independent investigation under way by the City Attorney and the Controller. The City Attorney is an independently elected official; the Controller operates independently of the Mayor’s Office. Whatever comes of the federal case, I am confident our City Attorney and Controller will uncover any improper actions that were taken and recommend reforms to ensure they never happen again. Once we have recommendations and analysis completed by these two independent offices, I will join my fellow elected officials to implement any reforms necessary to restore the public trust.

As I said, I’ve known Mohammed for more than 20 years, and as with so many others in our City government, I’ve been both a friend and a colleague. This situation has forced so many of us to examine our relationship.

And in the spirit of my directive to city employees to be as transparent as possible, I want to note that in my annual “Statement of Economic Interests,” due this coming April 1, I will voluntarily disclose a “gift” of approximately $5,600 from Mohammed Nuru.

Last year, my personal automobile had broken down and Mohammed, acting as my friend, took it to a private auto mechanic. The estimated cost of repairs seemed more than the 18-year-old car was worth, but Mohammed had it fixed. Later, when the car still wasn’t working, he helped secure a rental. The estimated value of those things is about $5,600. It had been my intention to sell the car (which is still not running consistently, even after the repairs) and reimburse Mohammed.

Now, gifts provided “by an individual with whom the official has a long term, close personal friendship unrelated to the official’s position” are not required to be reported under the Fair Political Practices Commission’s rules. But since I have not yet been able to sell the car — and given all that has now happened — I have chosen to make this voluntary disclosure.

I realize that my close friendship to someone accused of something so serious will undoubtedly affect my life, and maybe even my life’s work. It has happened before, with friends and loved ones and members of my broader community.

It is part of the reason this hurts so much; I have striven my entire life to rise above the negative stereotypes and harmful expectations cast upon myself and those around me, to perform a public service, and to earn the public’s trust.

I will not apologize for dating someone two decades ago. I will not apologize for remaining close friends with him and his family for 20 more years.

But neither will I make excuses for any misdeeds. He will have to live with any consequences, and we in government must work to ensure our institutions live up to the highest levels of integrity.

I have no doubt that some will seek to exploit what I have shared here, to harm me politically. I, and others, may be weighed down from guilt by association as a result of this episode.

But I can’t worry about that now. What’s important is that we all hold ourselves accountable to the people of San Francisco, and do our jobs to the best of our abilities, honestly and faithfully, as our oath requires.

We must continue to support the hard-working employees at our Public Works Department, who are out there every day cleaning our streets and striving to improve our City. Finally, we must take this opportunity to make necessary reforms to strengthen accountability in our departments and restore the public trust.