NASHVILLE (AP) — Embattled House Speaker Glen Casada says he's asking for multiple probes of the scandals surrounding his office, saying he takes "complete ownership" of exchanging sexually explicit text messages with a former top aide about women.

In a letter Wednesday, Casada said he wrote the Tennessee Bureau of Investigation and the District Attorneys General Conference asking them to investigate an email by his former Chief of Staff Cade Cothren. He also apologized for his own conduct.

The investigation, he says, would probe whether Cothren tampered with evidence by making it look like a student activist had emailed Casada in violation of bond conditions after his February arrest during protests at Casada's office.

Casada says he's confident the email wasn't forged.

Casada also wrote that he has asked the House Ethics Committee to investigate Cothren's employment termination and his work with legislative administration to review personnel policies and consider possible drug testing of new employees. Cothren acknowledged drug use in a legislative office several years ago.