NEW YORK (CBSNewYork) — The principal of a failing Bronx school was under investigation Monday night on allegations of grade fixing – changing scores so more students would pass.

As CBS2 Political Reporter Marcia Kramer reported, the mayor is vowing “serious consequences” for any wrongdoing.

Dewitt Clinton High School, at 100 W. Mosholu Pkwy. South in the Bedford Park section of the Bronx, is a struggling school. Low attendance and a graduation rate of just 45 percent put it on the endangered list.

But now, principal Santiago Taveras has come under investigation in the grade-fixing scandal – and it happens that Taveras is a former deputy chancellor in the city Department of Education.

His job was to close failing schools.

The investigations surrounding Taveras now alleges that he changed failing grades to passing grades without teachers’ consent.

For example, a senior who got a “no-show” grade in global history reportedly got it changed to a 75. Another student’s 55 in English was reportedly changed to a 90, and a failing algebra grade of 55 was reportedly changed to a passing 65.

Other grade-fixing scandals, such as that at John Dewey High School in Brooklyn, were reported by teachers. In this case, the city Department of Education discovered the problem itself.

“My Department of Education initiated that investigation,” said Mayor Bill de Blasio, “and that investigation will proceed promptly, and if we find any wrongdoing, there will be very serious consequences for the individual involved.”

Students at Dewitt Clinton, part of the Department of Education renewal program for failing schools, were outraged.

“It makes me upset. It’s going to make us look bad,” said student Kevin Bacchus. “I have 90s and I’m going to be questioned about my 90s.”

“Changing the grades is not going to help anything,” said student Shanice Cerby. “It’s not going to help the students. It’s not going to save the school.”

“We all have to earn our grades,” added student Sarojnie Dhanpat. “At some point, everyone has to earn their same grade.”

The principal reportedly urged teachers to raise their pass rates to 80 percent.

Devora Kaye, a spokeswoman for schools Chancellor Carmen Fariña, said that when Department of Education staffers “identified possible improprieties” at the school, the issues were immediately reported to prosecutors for investigation.