WASHINGTON (AP) — Police officials in the nation's capital have been facing recent questions about headline-making arrests — not of hardened street criminals but of their own officers.

In a single month, one District of Columbia police officer was accused of taking semi-nude pictures of a 15-year-old runaway and another was charged with running a prostitution operation involving teenage girls. A third was indicted on an attempted murder charge, accused of striking his wife in the head with a light fixture.

Police say the arrests aren't representative of the entire department, which includes about 4,500 officers and civilian employees. Still, more than 100 officers in the last five years have been arrested on charges ranging from traffic offenses to murder to money laundering, and the latest instances have increased concerns about training, supervision and accountability. The D.C. Council has set a hearing to discuss the problem and Police Chief Cathy Lanier has met with residents to assuage fears of a misbehaving department.

"We don't think we have a department out of control, and I think that oftentimes is the image that is portrayed," she said in an interview, noting that the majority of arrests are not for on-duty corruption but instead involve off-duty misconduct that is harder to police.

The hearing Friday will focus on how applicants are screened and what services are available to prevent alcohol abuse and domestic violence, two prevalent problems, said Councilmember Tommy Wells, who chairs the public safety committee.

"I think it's extremely important that the public have confidence in our police force and we've had three high-profile cases of serious police misconduct, albeit generally off-duty," Wells said.

Police department figures show the arrests of about 110 police officers, for both on- and off-duty conduct, since 2009. Many of the arrests involved traffic violations or involved cases that were dropped or ended in acquittal.

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Among the most serious cases was Richmond Phillips, who received life without parole last year for the slayings of his mistress and baby daughter. Wendel Palmer was convicted last year of sexually abusing a girl who participated in his church choir, while Kenneth Furr received a 14-month sentence for an armed altercation that began after prosecutors say he solicited sex from a transgender prostitute.

Lanier has said many of the arrested officers were brought onto the force during a time of lax hiring standards and wouldn't be qualified to serve today. She said that in some cases the arbitration process has required the department to rehire officers it fired. She said the department has dramatically tightened its recruitment practices to mandate polygraph exams and that only one of about 25 applicants is now hired.

The department also tracks warning signs like missed commitments and abuse of sick leave. And it requires officers to report off-duty arrests, which Lanier contends can make the numbers look worse than in cities that lack that requirement.

"I feel comfortable that our recruiting process, the background screening we do, is as tight as we can get," Lanier said at the meeting. "But I also realize that there are people that are on the police department that came through at a time when there was not that strict background (check), and those are the people that we want to make sure that if they are involved in misconduct, that we weed those people out."

But resident Khadijah Tribble, 42, told the chief she was unconvinced the misconduct was isolated.

"Aren't these trends troubling and isn't it worth our due diligence to do a thorough, independent investigation of this trend?" Tribble said in an interview.

Robert Kane, the director of the Drexel University criminal justice program who has studied police misconduct, said the number of arrests wasn't necessarily shocking for a big-city police department.

At least 43 New York City police officers are known to have been arrested between 2011 and 2013 on charges including gun-running, drunken driving, perjury, a ticket-fixing scam and a cannibalism plot. A Los Angeles police officer was charged with stomping a handcuffed woman who later lost consciousness and died. Dozens of Memphis, Tenn., officers have been arrested in recent years.

Kane said that while on-duty police misconduct can be reliably defined, off-duty misbehavior by officers is studied less often.

"We know what factors explain police misconduct, when police officers stop people and extort money from them," he said. "What do we know about officers who walk into a liquor store when off-duty and rob it at gunpoint for some beer?"

In D.C., the first of the recent arrests was on December 2 when officer Marc Washington was charged with taking semi-nude pictures while on-duty of a teenage runaway who had just returned home. Authorities say after responding to the girl's apartment, he directed her into her bedroom and told her to undress so he could photograph injuries. He was arrested after the girl alerted her mother, who contacted police. Soon after being released from jail, Washington was dead from an apparent suicide.

The following week brought the off-duty arrest of Linwood Barnhill Jr., a 24-year-veteran who was charged after police came to his apartment and found a 16-year-old girl who had been reported missing. The girl told police Barnhill had photographed her and offered to pay her to have sex with other men, allegations also made by a second teenager. His lawyer says Barnhill never threatened anyone.

Lanier acknowledged the arrests, especially for on-duty conduct, have shaken the department. But she said she hopes the sight of handcuffed officers sends a message to other officers who would break the law.

"We would like the officers to know that if there's somebody in our midst that is committing criminal conduct and we become aware of it, we will lock them up," Lanier said. "We don't need somebody else to lock them up. We will lock you up."