A shooting death that followed a dispute in a liquor store parking lot on a warm spring evening nearly five years ago defines the face of the unsolved homicide in Los Angeles County, according to more than a decade’s worth of law enforcement data analyzed by this news organization.

Killed was Luis Arturo Palomera. A gunman apparently intent on finishing the dispute drove through an alley in front of Palomera’s parents’ Baldwin Park house and shot him in the back as Palomera talked with a friend.

Everything about Palomera — his age, 25, his race, Latino, and that he was gunned down — make him the typical victim of an unsolved homicide in L.A. County. The homicides of Latino males aged 19 to 35 go unsolved at a rate double that of the typical homicide victim, an analysis of the data shows.

In Palomera’s case, the killer may have fled to Mexico, according to his mother, Armida Palomera.

“If they know who did it and they know he’s in Mexico, then what does it take to do something about it,” Armida, 47, said in a recent interview. “I don’t want something to happen 20 years from now — when I’m dead.”

Many killers elude capture. In L.A. County, of the 11,244 homicides committed in an 11-year span, 4,862 — or 46 percent — remain unsolved, according to an analysis of law enforcement data. The clearance rate for all homicides in L.A. County over the span of the study was 54 percent while the national average for the same time period was 63 percent, according to statistics gathered by the FBI.

• VIDEO: Behind the numbers

The homicide information analyzed by this news organization is the first-of-its-kind database of unsolved homicide cases in L.A. County from Jan. 1, 2000, through Dec. 31, 2010. A 54 percent countywide clearance is not satisfactory, said L.A. County Sheriff Jim McDonnell. “In the real world, these are people’s lives and their memories and how they view the system,” McDonnell said. “You can never bring the person back, but at least there is some level of justice when people are held accountable; it adds to the credibility of the system.”

In his experience as a homicide detective in the early 1980s for the Los Angeles Police Department, McDonnell said he and his colleagues took the homicides they investigated personally.

“It doesn’t matter the race, sex, age of the victim, their goal is to solve it,” McDonnell said. “It’s the ultimate puzzle and there is no more significant crime against mankind than to kill another man. It transcends race or any other factor. You want to give a victim’s family comfort and you also want to take a dangerous person off the streets.”

Los Angeles Police Detective Meghan Aguilar said each homicide has its own unique challenges when it comes to finding a solution, but cautioned against reading into the data.

“The information from the particular reports you requested do not constitute a complete record of all (LAPD) homicides and their investigative status,” Aguilar said in an email. “…any analysis or conclusions drawn from the data cannot be accurate.”

The data analysis is based on 11,244 homicides recorded over the time period by the L. A. County Department of Medical Examiner-Coroner. Law enforcement agencies throughout the county provided the statuses of 10,501 homicide investigations. Information was not provided on 682 cases and detectives determined an additional 61 deaths were no longer considered homicides.

• Database: Los Angeles County’s Unsolved Homicides

In 44 percent of the cases in which the status was known, a suspect had been arrested. About 10 percent of the homicides are considered “solved by other means” either because the suspect had died, the case was deemed a murder-suicide or police investigators determined the death to be justified, as in the case of an officer-involved shooting.

“This is eye-popping data when you look at it in detail,” said Jody Armour, the Roy P. Crocker Professor of Law at USC. “You see stark differences in just homicide numbers and (clearance) rates as a function of race….It’s a window on race and class and crime in L.A. and therefore in much of America.”

African Americans, and to a lesser extent Latinos, are much more likely to be a victim of violent crime in their own communities than whites, Armour said.

Of the 4,862 unsolved cases, males represent more than 90 percent of the deceased. Of those, 90 percent were shot to death, like Palomera, who was a resident of El Monte when he was killed on May 21, 2010.

Latino victims make up half of the unsolved homicides.

Black victims

For black victims the numbers appear more stark. The data show it is more likely that a homicide of a black victim — male and female — will go unsolved. Among those cases is the shooting death of Dwight Caldwell, 25, in North Long Beach on May 2, 2009.

Standing at 52nd Street and Orange Avenue, Caldwell was shot repeatedly when a car pulled up and a gunman opened fire, according to an autopsy report. He collapsed after running into a nearby residence. Caldwell died at Long Beach Memorial Medical Center. No weapon was left behind. However, three shell casings of an unknown caliber were later collected as evidence.

Half of the homicides of black victims remain unsolved. Black victims made up about 34 percent of all homicides recorded in L.A. County during the 11-year period.

Blacks and Latinos are killed most often because they are more likely to live in high crime and gang-affected areas where illegal weapons proliferate, said Jorja Leap, a professor at the UCLA Luskin School of Public Affairs and nationally recognized gang expert conducting a five-year research study evaluating the impact of Homeboy Industries, a gang-intervention and re-entry program in Los Angeles.

Those cases can also be harder to solve because witnesses are often reluctant to come forward out of fear of retaliation, she said.

For some families of young men across the Southland who are killed, there is a resignation the murder will never be solved, said Jane Bouffard, president of Justice for Homicide Victims Foundation. In 70 percent of the unsolved cases, the victims are men between the ages of 14 and 35, according to the data.

“The families kind of feel like the police just, say, ‘Oh well,’ ” Bouffard said. “I hate to say that because there are homicide detectives that are very, very caring and very diligent and want to solve each of them, but they have a big caseload and when they get called to a scene a lot of times they don’t have a lot of evidence because in those communities, people don’t come forward, so they don’t have anything to use to solve it with.”

Solving some easier

The database showed homicides involving white or Asian victims were more likely to be solved.

White victims accounted for 11 percent of the homicide cases but only about 6 percent of the unsolved homicides. Asians victims made up 3.5 percent of the homicides and 3 percent of the unsolved cases.

USC’s Armour said the lingering effects of racism and discrimination may account for some of the disparities.

The Rev. Martin Luther King Jr. “was fighting conscious discrimination — white-only fountains, black-only bathrooms,” Armour said. “These statistics may reveal a much more subtle form of discrimination that getting rid of Jim Crow didn’t get rid of and represents the next chapter in the MLK struggle.”

Armour acknowledged other factors could be at play as well.

• More Coverage: Getting Away With Murder

The steps police detectives take at the beginning of a homicide investigation can also affect clearance rates, said Charles Wellford, professor emeritus at the University of Maryland’s Department of Criminology and Criminal Justice. Modern training, technology and professional supervision can play key roles in a positive outcome.

For example, how quickly a detective can get to the scene of the homicide after the killing occurs can influence whether a case is solved, Wellford said. Some police departments require detectives to drive to the station to pick up a police vehicle before they drive out to a scene, losing precious and critical investigative time.

Challenges aside, Bouffard, a victim advocate whose parents were murdered, said unsolved homicides change families.

“It changes them,” she said. “They become very suspicious of the world and very suspicious of people. They lose hope in everything that the case will be solved.”

Staff writer Brenda Gazzar contributed to this report.