On the evening of Sept. 22, 2009, two men wearing hoodies and bandannas jumped out of a truck in front of a northwest Oklahoma City house and opened fire on a group of friends.

Shot five times, Bradley Wahnee, 19, a sophomore biology student at Oklahoma City University, died on a cracked concrete driveway beneath the branches of a large oak tree.

Almost seven years later, his killing remains unsolved.

Wahnee, who earned an academic scholarship to OCU, loved his 2009 black Dodge Challenger, bowling on Monday nights with his niece and nephew and eating lunch with his grandparents almost every day after class. He hoped to become a radiologist.

“We would love to have justice on Brad’s behalf,” said his mom, Kari Wahnee, who said her family is still looking to authorities for answers about her son’s killing. “Nothing would make us happier, but I don’t think the police or the court see it the way we see it. To them, it’s just another kid. It’s just another murder.”

It may be the most important function of law enforcement — bringing to justice those who take the life of another. But in Oklahoma City, getting away with murder is hardly uncommon. An analysis by The Oklahoman has found that since 2008 nearly half of all potentially prosecutable homicides ended like Wahnee’s, with the killer walking free. The percentages are even higher for homicides involving minority victims.

Police, prosecutors and other law enforcement experts cite a number of systemic factors that make it difficult for investigators to find, let alone convict, suspects in many homicide cases. They include:

• The random nature of some of the killings. With no obvious relationship between the killer and victim, investigators often are left with few leads to pursue.

• Witnesses unwilling to cooperate with investigators for fear of being implicated in a crime themselves or because they don’t trust law enforcement.

• Witnesses too intimidated or afraid to come forward or testify.

• Television crime shows that give some jurors an unrealistic expectation of the physical evidence investigators can produce, making it difficult for prosecutors to win a conviction.

• Juries that are sometimes less likely to convict a suspect if the victim had a criminal past.

But among the biggest issues — according to law enforcement officials, criminal justice scholars and other experts — is a lack of willingness among people to get involved, to report wrongdoing, to cooperate with authorities, to want to make their communities safer. Residents in many neighborhoods, and especially in predominantly minority areas, are reluctant to assist law enforcement, part of a “no-snitch” culture that authorities say can make solving a killing impossible.

“The police don’t necessarily solve crime,” Oklahoma City police Chief Bill Citty said. “We investigate it and find all the facts. The people solve crime. Witnesses solve crime.”

'Absolutely no trust'

Community leaders and experts respond that it's only understandable that some residents, especially poor minority residents, distrust or are unwilling to cooperate with authorities.

In the case of minority residents, the lack of trust reaches back decades and generations.

“On a local level, even in Oklahoma City, there is a deep level of distrust between African Americans and the police force," said Lawrence Ware, a pastor of Christian education at Prospect Baptist Church in northeast Oklahoma City.

The fact that so many killings go unsolved takes a profound toll and, in some cases, reinforces the negative perception that some communities have of authorities.

Among survivors, the unsolved death of a loved one can leave a “gaping hole” that can cause them to lose faith in the criminal justice system, said Dan Levey, executive director of the National Organization of Parents of Murdered Children.

Everyone grieves and responds to homicides differently, Levey said, but people whose loved ones’ deaths are unsolved yearn to know that the person who committed such a heinous crime won’t continue to victimize others and that their loved ones are not forgotten.

Read: Oklahoma City community leaders, residents discuss unsolved homicides during public forum

When no one goes to prison, it can add another layer of acute trauma that can become overwhelming and consuming for survivors, Levey said.

“You want to know that the person that willfully took your loved one’s life is going to be held accountable,” he said.

JoNita Normore of Oklahoma City said she felt abandoned by law enforcement in the years after her son, Ra’Mon Robinson, 25, was shot to death in 2009 at a northwest Oklahoma City apartment complex. Eventually, she said, detectives stopped answering her calls asking about his unsolved case.

“I had very high hopes in the beginning, but my high hopes went down,” Normore said. “I just had to put it in God’s hands and leave it there because I have absolutely no trust for our justice system.”

“I feel like people have forgotten about him,” Normore said of her son.

'Like going through hell'

Omeca Humphrey, of Oklahoma City, said detectives promised after her son was killed that they wouldn’t let his case slip through the cracks.

Tracey Humphrey, 19, was shot in the head in northwest Oklahoma City in the early hours of Sept. 26, 2010, as he and a friend were driving away from a club. He died days later at OU Medical Center.

Nearly six years later, police have made no arrests and Humphrey said investigators no longer return her calls.

Her son’s death left family members devastated, Humphrey said. Now, she said it feels like the case is “flapping in the wind.”

“It’s been like going through hell when you don’t have an answer or even an inkling on who did it, why they did it, why it’s not solved,” she said.

Oklahoma County District Attorney David Prater, whose office is tasked with prosecuting nearly every Oklahoma City homicide, said he empathized with such families.

“I’m not going to point fingers at them and say, ‘You shouldn’t feel that way,’” Prater said.

Oklahoma City homicide detectives also understand the frustration families feel, said Inspector Robbie Benavides, a 10-year veteran of the unit.

Detectives try to explain to victims' families that they won't be calling every day or every week to update them about what's happening with their loved one's case, he said. In most cases, that's simply because there's nothing new to say, Benavides said.

"We’ve had families call and say, 'I haven’t heard from you guys in several months, I haven’t heard from you in a year, what’s happening?'" Benavides said. "And we’re in the same position that we were a year ago."

When new information surfaces that might help a case, detectives don't share that information in great detail with victims' families to avoid jeopardizing the investigation, Benavides said.

Most frustrating is when investigators think they know who committed a killing but can't prove it, Benavides said. Investigators think about those cases all the time.

"You keep telling yourself, 'Did anything else come up?' And you go over the whole case again and you're still in the same spot you were three, four months ago. ... It's frustrating," Benavides said.

Citty, the police chief, worked homicide in the 1980s. Detectives not only want to solve every case, he said, they want convictions.

“When they fall apart, it’s very frustrating,” Citty said.

By the numbers

The Oklahoman’s analysis examined every homicide that occurred between Jan. 1, 2008, and June 30, 2015. During that period, 534 people died in Oklahoma City at the hands of another.

Ninety of the cases involved circumstances that made it unlikely anyone would ever be tried for a crime, including cases in which police officers justifiably killed a suspect, murder-suicides and justifiable homicides. Another 30 cases were still pending in court at the time of the analysis.

Of the 414 remaining cases, 196, or 47.3 percent, remained unsolved.

In 136 of those unsolved cases — 69.4 percent — police never even arrested a suspect. In others, police arrested a suspect but prosecutors didn't file charges, citing a lack of evidence. In some cases, prosecutors filed charges but later requested they be dismissed. In still others, prosecutors took the case to trial, but jurors acquitted the suspect.

The unsolved homicide victims included a cook, a retired bus driver and a motel owner. They included a cabbie, a college student and a trucker. There was an Army veteran, and a drug and alcohol abuse counselor. There were also drug dealers, gangbangers and dozens of people with previous criminal convictions.

Read: City council members react to analysis of homicide cases in Oklahoma City

In the overwhelming majority of unsolved cases — 82 percent — the victims were men. Sixteen percent were women. Three victims were unborn children whose sexes were unknown.

The Oklahoman’s analysis showed that blacks made up an inordinate share of homicides, both solved and unsolved.

While blacks make up only 14 percent of Oklahoma City’s population, they accounted for 46 percent of the city’s homicide victims. They made up an even larger share of the city’s unsolved homicides, 52.6 percent, compared to 24.5 percent for whites and 16.8 percent for Hispanics.

The average age of the unsolved homicide victims was 33.

Citty, who became police chief in 2003, said he found it “not too surprising” to learn that nearly half the city’s homicides go unsolved.

Citty said he wouldn’t be completely satisfied unless police made an arrest in every homicide. But, he added, that is an unrealistic expectation, given the challenges investigators face.

“We’ve worked hard at trying to get them solved,” Citty said. “In many cases, it’s just not going to happen.”

Oklahoma City Police Chief Bill Citty. AP Photo

Disaffecting neighborhoods

That only about half of all Oklahoma City homicides ended up in a conviction surprised ACLU Oklahoma legal director Brady Henderson. The racial disparity in the numbers did not.

“I have seen many instances where you have, really, whole neighborhoods, whole segments of communities that are predominantly people of color, where there is a lot of distrust for the police,” Henderson said. “And people not only don’t want to talk to detectives, don’t want to give up information, in many cases they don’t even want to call. I mean, literally, they’re not calling 911 when the emergency even happens.”

That so-called “no snitch” culture is a holdover from a time when gang violence was more self-contained than it is today, said Grace Franklin, a co-founder of the activist group OKC Artists for Justice.

Gangs abided by certain rules, Franklin said — areas near schools were off limits and people who weren’t gang members weren’t to be touched. Gangs enforced those rules themselves, she said.

But today, those rules no longer exist. Gang violence spills over into entire neighborhoods, and law-abiding residents who aren’t involved get hurt or killed. But the “no snitch” rule is still enforced, she said.

If residents don’t cooperate with police, the problem will never go away, Franklin said. But she said it’s understandable that northeast Oklahoma City residents wouldn’t feel safe talking to investigators after suffering decades of what Franklin called poor treatment at the hands of police. Most people in northeast Oklahoma City know people who have called the police, only to be treated as suspects themselves, she said.

Some witnesses are reluctant to talk to investigators for fear that word could get around that they’re cooperating with authorities, she said.

Others may worry about the police themselves, she said.

Even a witness who is willing to talk to the police may not be able to tell everything he or she knows. If police lose patience and lock the witness up for obstruction, that person could miss days or even weeks of work and possibly lose a job, she said.

“Sometimes the help comes at such a high price that people won’t (call) when they really need help,” she said.

Across the country, witness cooperation remains the biggest challenge in trying to solve and prosecute homicide cases, said David LaBahn, president of the Association of Prosecuting Attorneys, a Washington, D.C., nonprofit.

If no one will step forward and cooperate with police, or if people won’t come to court to testify, there isn’t much the system can do, LaBahn said.

“Our criminal justice system is only as good as the communities that support it,” LaBahn said.

Oklahoma County District Attorney David Prater. Jim Beckel / The Oklahoman

Uncooperative witnesses

Part of the problem is that, oftentimes, witnesses live in the area where the crime occurred and they’re nervous about what will happen if they talk to police, said Benavides, the homicide detective. And police acknowledge they can offer little in the way of protection.

“If I could tell them nothing’s going to happen to them I would, but we don’t do that because we just don’t know,” he said.

And too often, those witnesses are unwilling to cooperate either because they’re closely tied to the perpetrator in some way or they’re afraid of retaliation if they talk to investigators or testify at trial, said Prater, who has served as the county’s district attorney since 2007.

In some instances, even when investigators have enough evidence to take a suspect to court, the case falls apart because witnesses are too afraid to testify.

“It happens too often," Prater said.

In a few cases, witnesses have received calls from untraceable phone numbers warning them that they would be killed if they testified, Prater said.

“We have gang members who will come sit in the back of the courtroom sometimes during preliminary hearings when their buddy’s on trial in an attempt to coerce, in an attempt to threaten and scare witnesses who are there to testify,” Prater said.

Sometimes, especially in cases where the victim has a criminal past, jurors simply lack sympathy.

Prater said he’s seen a number of acquittals in which his prosecutors proved the case beyond a reasonable doubt, but couldn’t win a conviction because jurors didn’t like the victim.

“As a human being, I get that,” Prater said.

Still, he said, someone needs to be held accountable for the crime.

Lack of evidence

Other hurdles to conviction can involve the physical evidence itself.

The amount of time between when a homicide occurs and when it’s reported to police is critical, said David Carter, a professor in the school of criminal justice at Michigan State University. The quicker police respond, the more likely they are to find evidence that hasn’t deteriorated or been destroyed or removed, the more likely there are to be witnesses around and the more likely the killer is to be nearby.

“As the time increases, all those factors decrease,” Carter said.

The longer a homicide investigation goes, the more difficult it becomes to solve. Investigators have a lot of tools they can use to collect and analyze evidence, but they still have to find it and be able to match it up to a suspect, said Citty, the police chief. Over time, detectives start running out of leads and clues, he said.

Another challenge for detectives is that some jurors believe what they see on television shows like “CSI: Crime Scene Investigation.”

“They solve every case and they do miraculous things with evidence, and that’s just not real,” Citty said. “ … When you don’t have that, in many cases, I think that they feel like you don’t have enough evidence.”

Obtaining physical evidence often is much easier in domestic cases or homicides where the victim and the perpetrator had close contact. Domestic violence homicides, which are usually easier for police to solve, have been declining during the past 20 years or so, said Scott Decker, a criminology professor at Arizona State University. Meanwhile, he said, gang and drug-related homicides have increased or remained constant. Those types of crimes often are more difficult to solve because they typically involve strangers or people who are not very familiar with each other.

In many gang-related homicides, physical evidence is limited. In those instances, investigators, instead, often must rely heavily on witnesses, who often can't be found or are reluctant to testify.

Building trust

When trust breaks down between a community and those charged with upholding the law, it can take a long time — sometimes a generation or longer — to repair, said Henderson, of the ACLU.

He praised efforts like the Police and Community Trust initiative, or PACT, an effort by several Oklahoma law enforcement agencies to build trust within their communities, including holding forums and identifying and addressing areas of public concern.

The Oklahoma City Police Department is doing a good job of trying to talk to people and listen to people through initiatives such as town hall meetings and “Coffee with a Cop” sessions, Henderson said.

Another program, the Oklahoma City Police Athletic League, works to prevent crime and build relationships by offering athletic and educational activities for children from high-risk neighborhoods.

Prater acknowledged that law enforcement in Oklahoma City has not always done a good job of communicating with minority communities.

“It’s not ever malicious,” Prater said. “But again, if it’s something that’s affecting your community, you want to have that explanation.”

Citty often talks about the need to hire additional minority officers so that the department more closely reflects the community it serves.

Henderson, the ACLU official, said the more people get used to cooperating with and trusting authorities, the more information is going to flow from the community, including about unsolved homicides.

“It’s going to take many years for those dividends to pay off, but I think they will,” Henderson said.

In the meantime, Kari Wahnee, mother of the OCU student whose 2009 homicide remains unsolved, continues to pray for answers about who took the life of her son.

"You never know at any time what’s going to make a difference," Wahnee said. "That’s always our hope. ... There are cold cases that get solved all the time, and that gives us hope. It almost makes me a little jealous when I see other people and their crime has been solved and their justice has been obtained, but for Brad, we’re still waiting on that day."