Some Springfield parents learned this week that the state invalidated three years of their kids’ elementary school test results. This comes after an investigation that found test booklets were tampered with to improve scores.

In October of last year, a Springfield TV station reported on what it called “extraordinary” test scores at Dryden School, which the principal at the time called “unbelievable.”

They were tops or near tops in Massachusetts. Dryden’s test scores caught the attention of Massachusetts officials, who found large increases in student achievement from one year to the next.

In a letter to Springfield Superintendent Daniel Warwick in June, Massachusetts education commissioner Mitchell Chester said the state found evidence of tampering, including that Dryden test booklets contained “widespread” eraser marks, with incorrect answers changed to correct ones. Chester said there’s no evidence students cheated, and called the investigation “ongoing.”

In a statement, Superintendent Warwick says he has “little information” about that investigation. But he says he’s “always concerned with ensuring [the district’s] strict testing protocols are observed.”

According to the state, this is the ninth time since 2002 that it’s invalidated test scores.