D.C. Police Chief Cathy L. Lanier said Friday that the 4,000-member force has been stunned by sexual accusations against two officers and that authorities are examining their backgrounds and hiring history to determine if any warning signs were missed.

“One action like this tarnishes us all,” Lanier said, speaking publicly for the first time since one officer was arrested Monday on a charge of producing child pornography and a second was linked on Thursday to an alleged prostitution ring that included a teen girl.

“It only takes one cop to do one thing like this to shake everybody in our community,” Lanier said. As to why the second officer, a 24-year veteran, has not been arrested, she said detectives are building a case. That 47-year-old officer, who is not being named because he has not been charged, was hired in 1989, when the D.C. force had lowered standards to quickly add 1,500 officers in 20 months. A Washington Post investigation in 1994 found that graduates in those two years accounted for half the number of officers arrested or facing discipline problems.

Lanier said the officer hired in 1989 has had three sustained complaints but nothing that would indicate sexual misconduct. Hiring standards, she said, have since been tightened. Still, she said, “We’re still doing a deep-dive examination of what happened.”

Both cases involve officers assigned to the 7th District station in Southeast Washington, and each is being investigated in cases involving children who had run away from home. But, Lanier stressed, “I will say right now there is no connection that we are aware of between the two, at all.”

The officer who was charged Tuesday — Marc L. Washington, 32 — was arrested after he had gone, while on duty and in uniform, to the residence of a 15-year-old girl who had just returned after having run away, prosecutors said.

The girl told police that the officer, who was on duty and in uniform, entered her bedroom, closed the door and asked her to disrobe, telling her that he needed to take photos for evidence, according to court documents. Police said he deleted many of the images between the time the girl’s mother called 911 and he was arrested. Police said they recovered the photos and have put another officer on desk duty, saying they believe he tipped Washington off about his impending arrest.

During a hearing Friday, U.S. District Court Chief Judge Richard W. Roberts granted Washington’s petition to be released from jail pending trial. But the officer, who has been put on leave from the force, must present the court with the deed to his Maryland home to ensure his return to court.

Assistant U.S. Attorney Ari Redbord argued that Washington should be detained, saying he used his position to “prey” on juvenile girls. “He is a sexual predator who had a gun and a badge,” Redbord said. Redbord said authorities were trying to identify other potential victims.

Lanier said the other officer, whose apartment on Stanton Road was searched Wednesday, has not worked on the streets since September 2012, when he took injury leave and his police powers were taken away.

According to court documents, police who arrived at the apartment found marijuana and a 16-year-old girl, who had been reported missing. The girl told police that the officer had arranged for her to have sex with an older man in exchange for money. She told police that six other girls or young women worked out of the apartment as prostitutes.