(CNN) A police officer in Prince George's County, Maryland, was charged this week with raping a woman during a traffic stop . He's pleaded not guilty , but it's a disturbing headline -- even more disturbing when you consider there are hundreds more like him. 
 
 Yes, hundreds. According to research from Bowling Green State University , police officers in the US were charged with forcible rape 405 times between 2005 and 2013. That's an average of 45 a year. Forcible fondling was more common, with 636 instances. 
 
 Yet experts say those statistics are, by no means, comprehensive. Data on sexual assaults by police are almost nonexistent, they say. 
 
 "It's just not available at all," said Jonathan Blanks, a research associate with the Cato Institute's Project on Criminal Justice. "You can only crowdsource this info." 
 
 The BGSU researchers compiled their list by documenting cases of sworn nonfederal law enforcement officers who have been arrested. But the 2016 federally funded paper, " Police Integrity Lost: A Study of Law Enforcement Officers Arrested ," says the problem isn't limited to sexual assault. 
 
 "There are no comprehensive statistics available on problems with police integrity," the report says, and no government entity collects data on police who are arrested. 
 
 It adds, "Police sexual misconduct and cases of police sexual violence are often referred to as hidden offenses, and studies on police sexual misconduct are usually based on small samples or derived from officer surveys that are threatened by a reluctance to reveal these cases." 
 
 The nation's foremost researchers on the subject, thus, must often rely on published media reports. The BGSU numbers, for instance, are the result of Google alerts on 48 search terms entered by researchers. The scholars then follow each case through adjudication. 
 
 While those numbers represent a fair portion of cases, arrests rely on a victim making a report and a law enforcement agency making that report public, after an arrest or otherwise. With sexual assaults by police officers, neither is guaranteed. 
 
 Why the numbers are lacking 
 
 One of the greatest impediments to understanding the scope of police sexual assault is the victims' reluctance to report the crime. 
 
 "Who do you call when your rapist or offender is a police officer? What a scary situation that must be," said Philip Stinson, an associate professor of criminal justice who served as principal investigator for the police integrity paper and whose research assistants maintain the BGSU database. 
 
 No one interviewed for this story could give an estimate, even ballpark, on how underreported these types of crimes might be. 
 
 "I have to think it's a much worse problem than my data suggests," said Stinson, himself a former police officer. 
 
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 There are several reasons behind the muddy data. The federal government cannot compel states to make the nation's 18,000 law enforcement agencies report the numbers. Even if they could, the Justice Department wouldn't have the resources to oversee and maintain such a database, Blanks said. 
 
 Unions also work hard to protect police officers and their reputations, he said. 
 
 "They don't want their officers and membership shamed if something goes wrong," Blanks said. 
 
 There also can be legal hurdles to obtaining basic information in such cases, he said, "and that's on purpose." Some states' laws shield the identities of police officers who commit crimes, he said, while some jurisdictions include nondisclosure agreements in victim settlements. 
 
 "The system is rigged to protect police officers from outside accountability," Blanks said. "The worst cops are going to get the most protection." 
 
 Victims include suspects and those police are supposed to protect 
 
 What data is available paints a jarring picture. One statistic from Stinson indicates that for every sexual assault that makes the news, there are almost always more victims -- on average, five more. 
 
 About half of the victims are children, researchers say. Stinson has gotten accustomed to hearing his research assistants proclaim during their work, "Oh my God, it's another 14-year-old." 
 
 Victims can include both the people police are supposed to be chasing and those they're charged with protecting, according to the police integrity paper. 
 
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 "Opportunities for sex-related police crime abound because officers operate in a low visibility environment with very little supervision," it says. "The potential victims of sex-related police crime include criminal suspects but also unaccompanied victims of crime." 
 
 Experts say officers who prey on people they encounter while on duty take advantage of the trust the public places in police as an institution. 
 
 "Police have a reputational advantage over anyone, especially someone accused of a crime," Blanks said, explaining that a regular Gallup poll shows again and again that police are third only to the military and small business owners in terms of trust. "People want to believe the police." 
 
 Offenders who seek to victimize people know this, experts say, and they strategically select victims, bolstering their chances of not getting caught. 
 
 Researchers find that a predominance of the victims fall into at least one of several categories: They have criminal records, are homeless, are sex workers or have issues with drug or alcohol abuse. Essentially, predatory cops are "picking on people who juries won't believe or who don't trust police," Stinson said. 
 
 The ripple effect 
 
 To be clear: The majority of police officers are good people, not sexual predators. Every expert interviewed for this story concurs on this point. But the problem is much larger than individual officers, said author and former Seattle Police Chief Norm Stamper. 
 
 "I think it's a huge problem," he said. "In reality, there's probably no law enforcement agency that has not had this problem." 
 
 The ripple effect can be devastating to a community. Stamper, who was a policeman in San Diego for 28 years before taking the helm in Seattle in 1994, recalled when California Highway Patrol officer Craig Peyer was convicted of the on-duty killing of student Cara Knott after a traffic stop. 
 
 No San Diego officer was tangentially involved, yet the department experienced enormous trust issues with the community, he said. Residents were fearful and some motorists were anxious about being pulled over, said Stamper, whose books address the "dark side" of policing and how to fix it. 
 
 "It cheats good cops," he said. "If a police officer is arrested for having fondled a DUI suspect in a jurisdiction, that affects all officers." 
 
 The trust issue is only exacerbated by the "blue wall" of silence that's erected when an officer is accused of a crime, he said. That's to be expected, Stamper said, because officers rely heavily on each other, especially in dangerous situations, and ratting out a colleague could mean trouble for an officer the next time she or he needs backup. 
 
 "If I'm a snitch, then the chance that my fellow officers will not have my back is significant," the former police chief said. 
 
 Some possible solutions 
 
 Stamper and others believe the solution lies in revamping police culture. 
 
 "The paramilitary, bureaucratic structure produces a dysfunctional culture," Stamper said, adding that for one of the "most delicate and demanding" jobs in America, officers largely go unsupervised. 
 
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 Specific to sexual assault, experts would like to see departments enact: 
 
 Policies "to make victims feel safe," Stinson said, which could include online or anonymous reporting and special officers trained in dealing with sexual assault victims 
 
 GPS tracking of officers, especially those with take-home vehicles, and monitoring of officers. If a supervisor notices a patrolman predominantly stops women between the ages of 18 and 30 at the same time of night in the same part of town, it would raise red flags 
 
 Rules forbidding departments from hiring officers who were fired from other agencies, which happens too frequently, Stamper said 
 
 Mandates that officers must activate their bodycams and dash cams and be punished if they don't. (This will actually vindicate officers more often than not, experts say) 
 
 Occasional sting operations, involving internal affairs, aimed at ensuring police officers are appropriately interacting with the public 
 
 "It's critical supervisors trust officers, but trust is earned," Stamper said, adding that the job is too important to trust officers blindly. 
 
 Police chiefs and sheriffs defending bad cops also erodes trust, Stamper said. He finds himself frustrated, he said, every time he sees a police executive step to a podium to decry the "bad apples" responsible for a crime that has tainted a department. 
 
 "If they repeatedly go back to that bank of microphones to bemoan the bad apples, it's time to look at the barrel. ... Look at the orchard," he said. 
 
 Are national standards in order? 
 
 Accountability is critical to changing police culture, experts say. 
 
 Stamper believes uniformity -- via the licensing of individual officers and the certification of police departments -- is key. 
 
 All 18,000 departments operate under their own rules, based on their traditions, policies, procedures and recruitment methods, he said. He believes creating national standards -- not for small things, but for larger constitutional issues -- could improve the quality of policing. 
 
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 If a licensed officer were to violate someone's rights -- by illegally searching or arresting them, manipulating evidence, using unnecessary force or, of course, engaging in sexually predatory behavior -- that officer's license would be yanked. 
 
 Likewise, a city police department with a pattern of violations could lose its certification and be taken over the by the county. An offending sheriff's department could be taken over by the state, he said. 
 
 It's pie in the sky, Stamper acknowledges, but until America changes the nature of the conversation around policing, things are destined to remain the same when it comes to crooked cops. 
 
 "The forces of resistance are powerful," he said. "If you push the system, it's going to push back with equal or greater force." ||||| Officer Ryan Macklin was in jail Tuesday on charges that he raped a woman he pulled over last week. News4's Tracee Wilkins reports. 
 
 A Prince George's County police officer in Maryland has been arrested on rape charges after a woman living in the United States illegally told police he pulled her over and attacked her. 
 
 Officer 1st Class Ryan Macklin, a six-year veteran of the department, was arrested on charges including rape and assault, Chief Hank Stawinski announced Monday night. The officer has been suspended without pay. 
 
 The woman told police the officer pulled her over about 1 a.m. Thursday on University Boulevard in Langley Park. Then, she said he forced her to perform a sex act in her car in a nearby parking lot. 
 
 She is an undocumented immigrant, sources told NBC Washington. 
 
 Prince George's Officer Arrested on Rape Charges 
 
 A Prince George's County officer is accused of raping a woman he pulled over. News4's Shomari Stone has the story. (Published Monday, Oct. 15, 2018) 
 
 "The charges against this officer are highly troubling. Officers take an oath to protect others, not to abuse their authority in order to victimize someone," Stawinski said. "Those who live and work in Prince George's County deserve the very best from the men and women of this department." 
 
 Police do not believe the officer targeted the woman because of her immigration status, the chief said. 
 
 It was not immediately clear if Macklin had a lawyer. He was in jail Tuesday and set to appear in court for a bond review the following day. 
 
 Macklin was named a patrol officer of the month in March 2014. He conducted a traffic stop and found a handgun, a police blog says. 
 
 It's unclear why he was in District 1, in Langley Park, the night of the crime. He was assigned to District 3, miles away in Palmer Park. 
 
 Donelan stressed that police were taking the allegation seriously. 
 
 Prince George's Officer Accused of Traffic Stop Sex Assault 
 
 A woman told police that a Prince George's County officer pulled her over and then sexually assaulted her. The alleged victim lives in the United States illegally, sources told News4. Tracee Wilkins reports. (Published Monday, Oct. 15, 2018) 
 
 "Within hours of the woman coming forward and telling us the events of what she says occurred to her, our officer was suspended. He is no longer a police officer. He can't act as a police officer. His police powers have been suspended," she said. 
 
 The officer has been stripped of his gun, badge and marked cruiser, Donelan said. 
 
 People living in the U.S. illegally are uniquely vulnerable to abuse by authorities, said Nick Katz, a lawyer with CASA de Maryland, an immigration advocacy and assistance organization. 
 
 "When the police are viewed as a gateway to immigration, to deportation, you're afraid to report crimes, especially something as intimate as sexual assault," he said. 
 
 Prince George's County police are looking into whether the officer may have assaulted more than one person. 
 
 "We have, during the course of the last 72 hours, come into information that leads us to believe that there may be additional people impacted by this officer's conduct," Stawinski said Monday night. 
 
 Anyone with information on the attack or other attacks is asked to call 301-772-4795. Help in English and Spanish is available. 
 
 Casa de Maryland also has resources available. They are available at 866-765-2272.
– A disturbing study out of Bowling Green State University has found that US police officers were charged in hundreds of rapes over the course of less than a decade. Per CNN, researchers behind the findings concluded that cops were charged in 405 forcible rapes in the nine years between 2005 and 2013. In order to compile their list, which includes other charges, researchers say they took to crowdsourcing because there is no comprehensive database that exists to document crimes committed by officers. As WVLT notes, study authors say the nature of their information gathering means the number could be higher. Experts also say victims of crimes perpetrated by police are frequently reluctant to come forward. The BSU study found that even more police officers were accused of crimes classified as forcible fondling, reporting 636 instances of such charges. (In just the last week, one Maryland officer was stripped of his badge after he was charged with the rape of an undocumented immigrant during a traffic stop.)