A white police officer has been targeting Latino drivers for traffic stops because of their ethnicity, a Los Angeles Police Department investigation concluded — marking the first time the department has found that one of its officers had engaged in racial or ethnic profiling.

For decades, the question of profiling — “biased policing,” in LAPD vernacular — has bedeviled the department. Accusations that the practice was commonplace throughout the 1970s and ‘80s alienated the LAPD from the city’s minority neighborhoods. And, despite dramatic reforms that have boosted the department’s image in recent years, complaints of profiling have persisted, with hundreds of officers being accused of bias each year. Until now, none of those complaints has been substantiated.

The finding is a milestone for the department and was met with praise from John Mack, a member of the department’s civilian oversight board and a longtime civil right activist who has been critical of the department’s handling of such cases.

“It means we’ve come a very long way,” he said.

The investigation into Patrick Smith, a 15-year veteran who worked alone on a motorcycle assignment in the department’s West Traffic Division, found that he was stopping Latinos based on their ethnicity. He is accused of deliberately misidentifying some Latinos as being white on his reports — presumably in an effort to conceal their ethnicity, according to multiple sources with knowledge of the case who requested their names not be used because police personnel issues are confidential.

At a meeting last month, LAPD Chief Charlie Beck reviewed the evidence against Smith and heard from members of his command staff who recommended the officer be found guilty. Beck signed off on the investigation’s findings and ordered Smith sent to a disciplinary hearing, where the department will attempt to have him fired, the sources said. In Los Angeles, the police chief cannot fire an officer unilaterally, but instead must let a three-person board hear the case and decide if the firing is warranted. The panel could also exonerate Smith, who was relieved of duty during the investigation, sources said.

Smith, 55, did not respond to an email seeking comment, and the Police Protective League, which represents rank-and-file officers, declined to comment.

Profiling complaints typically arise from traffic or pedestrian stops, in which the officer is accused of targeting a person solely because of his or her race, ethnicity or other form of outward appearance.

The question of how commonly profiling occurs in the LAPD has long been a topic of pointed debate. A 2008 study of LAPD data by a Yale researcher found blacks and Latinos were subjected to stops, frisks, searches and arrests at significantly higher rates than whites, regardless of whether they lived in high-crime neighborhoods. At the time, Beck’s predecessor, William J. Bratton, acknowledged isolated cases of profiling may occur but angrily dismissed the notion of a widespread, systemic problem. The data used in the study, he said, was several years old and did not reflect the attitudes of current LAPD officers.

Whether perception or reality, about 250 formal allegations are brought against officers each year. The fact that all the allegations, until Smith, were cleared was due to the murky nature of the allegation, police officials have said. Because profiling cases hinge on what officers are thinking in the moment they make a stop, it was all but impossible to determine whether they were motivated by a racial bias unless they confess, officials said. “We cannot climb inside the head of the officers,” was a familiar Bratton refrain.

That explanation wore increasingly thin on members of the Police Commission. At a meeting in 2010, Mack said, “I’ve heard many times that we can’t get inside an officer’s head, but somehow, some way, we need to figure out a way to get to the facts. I’m not talking about a witch hunt, but I am talking about reaching a point where we can say with confidence that these claims have been very fairly and very thoroughly investigated.”

The pressure on the department to overhaul its racial profiling investigations came, in large part, from the U.S. Department of Justice. Until 2009, the LAPD was under a federal consent decree that the Justice Department imposed in 2001 following the Rampart corruption scandal. It required the department to complete sweeping reforms on many issues and to submit to near-constant audits and monitoring.

The U.S. District Court judge who eventually freed the LAPD from the decree found that the department had completed most, but not all, of the required reforms. On racial profiling, the judge kept federal authorities in an oversight role for a time to assess the quality of the LAPD’s investigations and the Police Commission’s ability to monitor the issue.

Resentful of the continued federal oversight, department officials set about overhauling profiling inquiries. They created a special team of investigators to examine profiling complaints that focused on possible constitutional rights violations instead of trying to decipher the mind set of the officers.

The department suffered an embarrassing setback in 2010 when Justice Department officials became aware of a recording that captured two LAPD officers being dismissive of racial profiling complaints. “So what?” one said, when told that other officers had been accused of stopping a motorist because of his race. The second officer is heard saying that he “couldn’t do [his] job without racially profiling.”

The officers’ comments, Justice officials wrote in a letter to the LAPD, spoke to a “perception and attitude of some LAPD officers on the street” and suggested “a culture that is inimical to race-neutral policing.” That drew the ire of Beck, who said the Justice Department was unfairly using a few examples to make the case for a widespread problem.

Since then, the ongoing work of the new bias investigation unit and increased oversight by the commission has satisfied Justice Department officials, who cleared the LAPD of continued oversight on the issue.

Smith, sources said, first came under suspicion when multiple people he stopped filed complaints against him. It is unknown how many people he is accused of improperly stopping or misidentifying in his records.

joel.rubin@latimes.com