Avondale -- Agua Fria school officials said on Friday they may never know how a mercury spill at one of their high schools.

District officials released a letter to the community. It said, “Indeed, we may never fully uncover the details regarding the cause of the mercury spill.”

The Feb. 12 spill at Agua Fria High School exposed more than 60 students and staff members to dangerous levels of mercury.

The letter said students may taken mercury from a science classroom.

“The answers to why mercury may have been in the room and for how long remain unknown,” the letter said.

School officials said they were “unaware of the presence of mercury” on the campus at Agua Fria High School until the spill happened.

They also said they have “conflicting accounts” about the spill.

Avondale police are telling a different story. They say they know exactly how the spill happened.

They seized thousands of documents from the Agua Fria School District Thursday.

They said they’re finishing their investigation into how the spill happened and will release their finding soon.

After weeks of stonewalling a KPHO reporter, an Agua Fria school official finally agreed to talk to her Friday morning after a two and a-half hour meeting with their lawyers.

However, Agua Fria Assistant Superintendent Lexi Cunningham still didn’t answer basic questions about the spill.

We wanted to know why she assigned a teacher involved with the spill to teach science at another high school.

Cunningham responded, “I’m just going to have to tell you, and I know you’re not happy with the answer that it is an ongoing investigation and at this time we’re not at liberty to discuss student and personnel issues.”

CBS 5 has also learned school officials may be in trouble with the EPA. In an e-mail date Feb. 13, it says the EPA put the district “on notice” that they are a “potentially responsible party” for the mercury spill.