Just days after three Philadelphia school principals were fired for alleged cheating, news comes that the Pennsylvania attorney general’s office is conducting a criminal investigation into widespread cheating involving more than 100 educators around the city.

The Philadelphia Inquirer cites sources with knowledge of the criminal inquiry in reporting the attorney general’s involvement, as well as a grand jury to probe a growing scandal that has already ensnared 138 teachers and principals from schools all over the city.

Meanwhile, an official with the union that represents Philadelphia school administrators is blaming the alleged cheating that took place at 53 district schools and three city charter schools on high-stakes testing, and ultimatums from higher-ups to reach performance plateaus.

"Do you know how many of us sat in meetings with our bosses and were told, 'You have to bring your scores up'?" Robert McGrogan, a one-time Philadelphia principal told the Inquirer. "There was no how-to book given to us."

On Thursday, The School Reform Commission – or the state-run agency that has overseen Philadelphia’s public schools since Pennsylvania assumed responsibility for the city’s school district in 2001 – reportedly fired three city principals: Deidre Bennett of Cassidy Elementary, Michelle Burns of Kensington Urban Education Academy and Marla Travis-Curtis of Lamberton Elementary.

The attorney general’s probe reportedly comes after a state-run analysis of exams taken around Pennsylvania in 2009 uncovered suspicious patterns of erasures.

The 53 Philadelphia schools -- about 20 percent of the district’s total number of public educational institutions -- come, as the Inquirer wrote, “from every part of the city and span every grade level,” and include some of the highest-achieving schools in the city.

Click for the story from the Philadelphia Inquirer.