A pair of senior GOP lawmakers said former Environmental Protection Agency (EPA) Administrator Lisa Jackson might have “intentionally” violated public records laws.

The revelation that Jackson asked to communicate with a Siemens official through her personal email account indicated the ex-EPA chief skirted federal sunshine laws, said a letter from House Oversight and Government Reform Committee Chairman Darrell Issa (R-Calif.) and Sen. David Vitter (R-La.), the Senate Environment and Public Works Committee’s top Republican.

“We are concerned that your use of a non-official e-mail account was a deliberate attempt to circumvent federal transparency laws and Congressional oversight. Accordingly, we are writing to request your cooperation as the Committee investigates this matter,” the Thursday letter states.

Vitter and Issa requested all correspondence from Jackson’s personal email account spanning the duration of her EPA tenure that “refer or relate” to official business.