OAKLAND, Calif. (KRON) – Oakland police said on Friday that an investigation into allegations that officers committed sexual misconduct with a minor began after an officer committed suicide.

Oakland Police Chief Sean Whent said at a news conference on Friday that the suicide investigation prompted the sexual misconduct probe, although he did not say how.

The Oakland Police Department has been rocked by the recent public disclosure that 30-year-old Officer Brendan O’Brien committed suicide last Sept. 25 and that his wife, Irma Huerta-Lopez, committed suicide on June 16, 2014.

Whent said he was “very concerned” about Huerta-Lopez’s death and ordered “a very thorough investigation” that included senior homicide investigators to determine if it was a suicide or a homicide.

But he said the investigation concluded that her death was a suicide, even though there were two gunshot holes at the couple’s apartment in the 8000 block of Greenridge Drive in the Oakland hills.

Whent said it’s “not uncommon” for people who commit suicide to fire two shots and gunshot residue was found on Huerta-Lopez’s hands.

Residue was also found on O’Brien’s hands, but police said that may have been a result handling weapons as part of his duties as an officer.

Whent also confirmed the sexual misconduct probe involves allegations that a minor was involved. KRON was the first to break this story on Tuesday.

City officials said the district attorney’s office will investigate the officer’s suicide, the suicide a year earlier of his wife and the sexual misconduct allegations. The allegations have prompted the department to put three officers on administrative leave.

Whent said the sexual misconduct allegations against the three officers “are extremely troubling” and he has asked his department’s inspector general to look at all alleged officer misconduct incidents in the past several years.

Whent declined to say whether other officers have been implicated, only saying the investigation was ongoing.

Whent said many of the incidents involved conduct by officers when they were off duty but he expects his officers to maintain high standards both on and off duty.

Whent said the “overwhelming majority” of his officers are honest and hard-working but he said the recent misconduct allegations “have marred our reputation.”

Oakland Mayor Libby Schaaf said that a series of recent misconduct allegations against some of the city’s police officers, including sexual misconduct with a minor, are “very disturbing” and could hurt efforts to build trust with the public.

Speaking at a late afternoon news conference at City Hall, Schaaf said, “This type of misconduct doesn’t do justice to the citizens of Oakland and does an injustice to a (police) department that has made tremendous progress” in making reforms to comply with the 2003 settlement of a major misconduct lawsuit.

Schaaf said, “It’s truly tragic that this conduct is happening at this time. Although there’s still more work to do, the department has worked hard to develop the public’s trust.”

Schaaf said that as of Friday, the Alameda County District Attorney’s Office has agreed to conduct parallel and independent investigations of the sexual misconduct allegations as well as of the apparent suicides of O’Brien and Huerta-Lopez.

She said that to make sure that the District Attorney’s investigations are unbiased, no former Oakland police officers who work as investigators for the District Attorney will be involved in the probes.

Schaaf said she also issued an executive order requiring that the District Attorney’s Office be notified of any future suspicions of wrongdoing on the part of Oakland officers.

Schaaf also said:

We will look at cases of unfortunate series of off duty misconduct over the years. We want to ensure that all of their employees are of the highest morals not only on duty, but also off duty. We recognize that even the suspicion of misconduct can damage the trust that we’ve worked so hard to be built in this community. We owe it to our residents to be beyond doubt that this department holds its officers to the highest morals both on and off duty. We know that this department needs to be the trusted guardians of the community and we cannot do it with these types of clouds over the department, which is why we will keep trying to hold everyone accountable.

There are several former Oakland police employees that work now in the District Attorney’s, and they are being held away from the ongoing investigation, police said.

In April, Officer Cullen Faeth was charged with misdemeanor battery, trespassing and refusing to leave private property for an alleged drunken assault on a woman and her husband at their home in the Oakland hills in December. He’s on paid administrative leave.

Also in April, Officer Matthew Santos was fired and was charged with two felony counts for allegedly using a gun while off-duty to threaten a man who was painting his apartment door in Emeryville on Feb. 17.

Here is our Facebook live video of the news conference:

The Associated Press, Bay City News, and KRON’s Clemence Robineau contributed to this report