A New Orleans charter high school whose impressive test scores plummeted under the watchful eye of monitors is under investigation by the state Inspector General’s Office, officials said this week.

The school, L.B. Landry-O. Perry Walker High School in Algiers, is managed by the Algiers Charter School Association, one of the largest charter operators in the city.

That group fired its chief executive officer, Adrian Morgan, with little public discussion in January, more than a year after he informed board members of potential test cheating.

Landry-Walker’s principal, veteran educator Mary Laurie, is still employed.

This latest cheating allegation against the city’s closely watched collection of charter schools, if proven true, would again showcase the tremendous temptation that educators and students who live and die by their scores face.

Louisiana’s public high schools receive performance scores annually based on test scores and other measures, and low scores can mean state takeover for conventional schools and closure for charters.

High school students also must pass three of the state’s six subject end-of-course exams — the same exams in question in the Landry-Walker probe — to receive their diplomas.

In the face of such high stakes, at least four schools in Orleans Parish have been implicated in well-publicized cheating incidents or allegations on state tests in recent years, and a few dozen others have been flagged after state examinations found suspicious erasures, plagiarism and other test problems.

The state’s response in many cases has been to invalidate tests, send extra monitors to school testing sites or refer serious problems to the Inspector General’s Office.

Officials took the latter two actions in the case of Landry-Walker, state Education Superintendent John White and Recovery School District Superintendent Patrick Dobard said in letters to education leaders this week.

The Inspector General’s Office is investigating the affair, both men said.

The school is accused of teacher-led cheating.

“As it is an investigation of compliance with criminal laws, it is unlikely the investigative agency will have much to say publicly on the matter, but we continue to refer all questions to the inspector general,” White wrote Wednesday.

Landry-Walker, the product of a 2013 merger between the failing L.B. Landry High and the B-rated O.P. Walker High, first drew skepticism when its 2013-14 end-of-course exams in some subjects were noticeably better than either school had scored alone.

Of particular interest was a huge jump in the percentage of students scoring a state designation of “excellent,” the highest achievement label given, in geometry. About 78 percent of Landry-Walker test-takers hit that mark in 2013-14, compared with Landry’s less than 1 percent and Walker’s 12 percent the year before.

The school’s 2013-14 geometry scores bested even Lusher Charter School, a selective-admissions high achiever school, where only 73 percent of test-takers scored in that range.

It was not clear Friday how many 2013-14 test takers at the merged school were students at either Landry or Walker the previous year.

The upswing in scores troubled people both in and outside of the city’s education circles, so much so that Margaret Raymond, of Stanford University’s Center for Research on Education Outcomes — one of the state’s education research partners — sent White a letter about it in July.

She said her office had tracked, over four years, the test performance of 83 Landry-Walker students who took the 2013-14 geometry test. They found largely consistent performance in math and reading scores from 2010 to 2012 but a huge score spike in both subject areas in 2013, the letter said. The jump “far exceeds anything we have seen from any school in any period of operation,” Raymond wrote.

The state also analyzed the 2013-14 results after they were released and “turned up multiple indicators of potential malfeasance,” Dobard wrote. State officials then referred the matter to the Inspector General’s Office and beefed up school monitoring.

Separately, the Algiers Charter School Association increased its own monitoring and hired the law firm Stone, Pigman, Walther, Wittmann to monitor test sessions and make test security recommendations to the association, sources told The New Orleans Advocate.

According to nola.com | The Times-Picayune, which first reported the cheating allegations this week, the organization’s internal probe also showed that dozens of students who did well on the state exam had done poorly in the class that preceded it or had done poorly on the ACT Explore exam, a national exam commonly given to assess academic readiness.

That investigation also showed that only 13 percent of the school’s seniors in 2014 cleared the academic bar necessary to receive any portion of the state’s Taylor Opportunity Program for Students scholarships, which pays students’ in-state college tuition if they meet certain academic requirements.

As state and local monitors moved in, test scores plunged. In 2014-15, only 27 percent of students scored an “excellent” in geometry. There also was a notable dip in biology, with 64 percent of test-takers scoring “good” — the second-highest scoring designation — in 2013-14 but only 37 percent doing so in 2014-15.

Meanwhile, Lusher’s score remained relatively consistent, with 68 percent of students scoring “excellent” in geometry in 2014-15, while 63 percent did so in biology, up from 59 percent the year before.

Reached by phone, Algiers Charter School Association spokeswoman Tammi Major would not answer questions about the probe on Friday, citing the pending Inspector General’s Office investigation.

In January, four months after the 2014-15 scores were publicly released, the association’s independent charter board fired Morgan, who had first alerted it to the cheating allegation. The board hired former Principal Rene Lewis Carter to temporarily fill that role, a decision the organization announced, then made official with a board vote.

Morgan would not comment on his firing or on the cheating probe Friday. He has since obtained a new job, as executive director of school turnaround for Yardstick Learning, a consulting firm.

The state inspector general, Stephen Street, also would not confirm or deny his office’s involvement in the case, as is his practice.

Teachers or administrators found to have participated in cheating could be in violation of laws that prohibit filing or maintaining false public records, abuse of office or malfeasance in office. They also could lose their teaching licenses.