BALTIMORE (AP) — State education officials say they are deeply concerned about the findings of an investigation into alleged grade-fixing in Maryland's second-largest school district.

An audit released Friday says almost 5,000 students graduating from Prince George's County schools this year and last year had late grade increases after final cutoff dates.

A sampling of roughly 1,200 students from that group found that the late changes affected final grades for more than 400 students. Half of them had grade changes with no documentation, and scores more had only limited documentation.

The report also found that many graduates had unlawful absences exceeding 10 days, and that 59 were ineligible to graduate.

Investigators were unable to determine graduation eligibility for almost 300 other students, or one-fourth of the population sample, because of insufficient documentation.