Prince George’s School Chief Executive Officer Kevin Maxwell. (Mark Gail/For The Washington Post)

CHARGES THAT systemic corruption in the Prince George’s County school system led to the fraudulent boosting of graduation rates should be examined by Maryland state education officials. The county’s residents need to know if school administrators engaged in unethical practices to burnish the system’s credentials, or if the school board’s small group of disaffected members is so reckless as to advance its interests by belittling the efforts of teachers and students. Whatever the answer, it is clear the struggling school system has issues it must confront.

The county has been roiled by allegations from four members of the 14-member school board of widespread wrongdoing, with “complicity at the highest levels of the school system” to change grades and give students credit for courses they did not take. The allegations were contained in a May 30 letter to Gov. Larry Hogan (R) asking for an investigation. The letter was first reported last Saturday by Fox 5 News.

Schools Chief Executive Officer Kevin Maxwell “categorically” denied what he called politically motivated charges and said he welcomed state education officials to “fully explore” the matter. He pointed out, though, that there already was a review by the state after the federal education department got an anonymous complaint last summer. The conclusion contained in a Jan. 30 letter from the state Department of Education’s chief academic officer: “There was not anything done to indicate grades had been manipulated nor that bullying had been used to ensure more students were being promoted or graduated.”

The four board members who signed the letter (Edward Burroughs III of District 8, David Murray of District 1, Raaheela Ahmed of District 5 and student member Juwan Blocker) admitted Tuesday they were “absolutely unaware” of the earlier investigation by the state education department. That tends to undermine the “due diligence” they say they used in looking into these issues. If, as they claim, there is “clear and convincing evidence” of wrongdoing from whistleblowers, why take it to the governor and not local law enforcement? Or, at the very least, tell other members of the board? Mr. Burroughs has been a frequent critic of Mr. Maxwell and opposed the extension of his contract; Mr. Murray and Ms. Ahmed abstained, and the student member can’t vote on personnel issues.

There has been significant improvement in the county’s graduation rate, from 74.1 percent in 2013 to 81.4 percent in 2016. School officials credit muscular intervention and new supports for students identified as at risk of not graduating. A change last year in grading policy that included elimination of grades below 50 percent — viewed by some critics as too lenient — also probably played a role. Teachers feeling pressure to graduate their students is not a bad thing if it results in doing more to help students achieve. There is a problem, though, if students are getting diplomas they didn’t earn.

It is important that state education officials, with some urgency, determine exactly what the facts are here. Whoever turns out to have been wrong should be held accountable.