(CNN) Dallas Police Deputy Chief Malik Aziz attributes it to the "Ferguson effect."
Potential recruits aren't stepping up to apply for police jobs like they used to because of negative perceptions of law enforcement, he said.
"Your biggest recruiting tool is not going out to churches or job fairs or anything like that," Aziz said. "Your biggest recruiter is a police officer in uniform who will say this is the best department ... and you should come join it now."
Proselytizing isn't what it used to be.
Aziz, chairman of the National Black Police Association, says it's even harder to attract African-American recruits, who might already have a fraught relationship with police.
Nevertheless, the percentage of minority police officers working in departments across the country has nearly doubled in the last 30 years. Public perception of racial bias among law enforcement, however, seems to have only strengthened over time.
Cell phone cameras may explain some of that mistrust. The recent caught-on-camera deaths of two African-American men at the hands of police officers have many Americans asking: Who wants to wear a badge and carry a gun? And, who is qualified to do so?
Some argue that the answer lies in diversity.
"People have a right to have a department that mirrors their community and some of the issues would be alleviated, but it's not a panacea to all the problems that happen," Aziz said. "As you saw from Ferguson, having a diverse police force can reduce some of the challenges and some of the barriers that exist between law enforcement and communities."
Community policing -- building close ties between officers and the communities they serve -- is the answer for Camden, New Jersey, police Chief Scott Thomson.
"The burden is on us not to sit back and keep doing what we're doing, expect the public to change it on its own," Thomson told CNN's W. Kamau Bell. "Here's what we can't deny is that we all have biases. There are implicit biases that end up shaping our actions. It's recognizing and learning how to deal and process it in a way to ensure equity is being exuded during that process."
Nationally, racial minorities made up 27% of local police officers in 2013, up from 25% in 2007 and 15% in 1987, according to a 2015 Bureau of Justice Statistics (BJS) report.
Black officers were 12% of local forces in 2013, up from 9% in 1987; 12% of officers were Hispanic or Latino in 2013, more than double the 5% in 1987. Asian officers accounted for 3% local police in 2013 and 2007, four times higher than in 1987.
Black citizens comprised 13.3% of the population in 2015; Hispanics or Latinos 17.6% and Asians 5.6% according to the U.S. Census.
The percentage of women officers also went up since 1987, from about 5% to 12%
Dallas, which is grieving the murders of five police officers by an African-American man angry over the police shootings of black men, has widely touted its de-escalation training and community policing as leading to a drop in arrest rates and excessive force complaints.
However, a 2015 report from the New York Times points out that Dallas, among other American cities, isn't keeping pace with its diverse population when it comes to recruiting and retaining an equally diverse police force, creating an "image problem."
"Despite having large Hispanic and black populations, Dallas' police department is more than half white," the report notes. "The imbalance is also prevalent in smaller towns across the metro area."
The racial disparity is not unique to Dallas.
"In hundreds of police departments across the country, the percentage of whites on the force is more than 30 percentage points higher than in the communities they serve, according to an analysis of a government survey of police departments."
Many departments have been diversified through consent decree.
Baton Rouge, where 37-year-old Alton Sterling was shot and killed by local police this month, beefed up its ranks of minorities and women at the request of the federal government. In the last two years, more minorities than whites have been hired to police the majority-black city, according to a report by The Advocate, a Baton Rouge newspaper. As recently as 2010, nearly two-thirds of the city's police officers were white.
Joining law enforcement is a tough sell to any population, said Gregory Thomas, president of the National Association of Black Law Enforcement Executives and an adviser to the Kings County, Brooklyn District Attorney's Office.
The physical hazards and uncompetitive salaries are enough to deter potential applicants. According to the Bureau of Labor Statistics (BLS), the median annual wage for police and sheriff's patrol officers last year was $58,320.
Minority communities have additional factors that may keep them away from the force.
A Governing magazine report analyzing the BJS numbers found that young black men are "disproportionately burdened with prior arrests, disqualifying them from police work."
Hispanics who have migrated from countries that grapple with police corruption may be loathe to join law enforcement, the report found.
Who wants to join a force that has been an antagonistic presence in their life?
"If you're a police department that has had a history of doing work that looks like it's racial profiling ... or you have a history of not engaging the community and being very forceful and disrespectful in general then it's tough for you to recruit that same base," Thomas said. "They're not going to want to even listen to you."
Despite the challenges, racial diversity in hiring is a must, he said, especially to bridge language and cultural gulfs.
"It's critical for people in diverse communities to see diverse police officers."
Thomas said he thinks departments are "doing the best they can but they're up against a wall" when it comes to diverse hiring. Retention is also an issue for minority officers, who may complain of feeling slighted during the promotions process, Thomas says.
"If you are an African-American male and you're being treated unfairly by your colleagues ... you are less likely to tell your daughter, son or neighbor to be a cop," Thomas said.
Corey Pegues, a retired New York Police Department deputy inspector, said racial profiling is why his sons refuse to follow in his footsteps.
Pegues, who is black, described a recent 40-minute ordeal in which his son's car was searched without cause, a search that ended only when the cops saw the name on his license and realized it was Corey "Jr."
"In the black community they hunt. In the white community they protect and serve," he said.
Still Pegues, who details his evolution from teenage drug dealer to law enforcement executive in his memoir "Once a Cop," encourages his sons to join law enforcement as his daughter did.
In a phone interview, he recalled growing up on welfare, turning to drug dealing to survive and why he still thinks police work is a viable way into a better life for anyone.
He doesn't see the solution to repairing the community's trust as hiring more cops of color but demanding better accountability for the bad apples.
"I don't care if they're white, black or Chinese. We need cops (who are) compassionate, cops who are going to go into these communities and do the right thing. It's nice to have a bunch of black cops, but if you got a bunch of black cops who are terrorizing the community, that's not good."
Pegues, who sparked much controversy by confessing his drug dealing past, says he didn't go to jail for dealing, partly due to police corruption.
Nevertheless, he described law enforcement as a noble calling, citing officers in Dallas who put themselves in danger to usher protesters to safety.
"It's a great job; it's one of the most honorable jobs you can have in America," he said.