Updated at 4:15 p.m. ET

A high-level investigation into chronic absenteeism in Washington, D.C., high schools has found that students across the city graduated despite missing more than 30 days of school in a single course, in violation of district policy.

The findings today follow an investigation late last year by WAMU and NPR Ed into widespread violations of this policy at Ballou High school. That reporting has led to two investigations and the placement of the school's principal, Yetunde Reeves, on administrative leave. Results from the other inquiry are expected later this month.

The report focused on Ballou High School but also reviewed absenteeism and graduation policies system-wide. It found that in recent years, the number of chronically absent students has increased and that more of them are graduating, despite.

This first investigation comes out of the D.C. Office of the State Superintendent (OSSE), which contracted with a private firm to look into what happened at Ballou and other high schools. That investigation was ordered by D.C. Mayor Muriel Bowser on Dec. 1.

"The huge investments we have made in our schools only work if students are sitting in the seats," Bowser said at a news conference today.

The OSSE findings also confirmed our reporting from the last school year at Ballou High School, citing violations, specifically, with 113 of 177 graduating students' records. Those include:

Antwan Wilson, the chancellor of the city's public schools, said he was "disappointed" by the findings, notably that "over 60 percent of students [were] graduating with excessive absences."

Wilson said that the school district's internal review also saw excessive passing rates for absent students across the city, specifically at Anacostia, Eastern, Woodson and Roosevelt High Schools where "we are in the process of trying to understand what's behind some of the numbers there."

"Failure is a part of life," Wilson added, but he said the district still needs to make sure that students adhere to policies and are set up for success.

Results from a full, district-wide investigation are expected at the end of this month.

Since publishing our initial report, WAMU and NPR Ed have heard from educators across the country that similar practices are taking place in their schools.

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