ST. LOUIS – A grand jury has been formed in the St. Louis Circuit Attorney's investigation into Governor Eric Greitens, and on Monday it issued a subpoena for the man who created the recordings at the middle of the scandal, according to the man's lawyer.

Democratic Circuit Attorney Kim Gardner announced her investigation on Jan. 11, a day after Greitens admitted to an extramarital affair. Al Watkins, the attorney for the ex-husband of the woman involved in the affair, turned over recordings to the Circuit Attorney's Office and FBI.

On Monday, a subpoena was issued by a grand jury formed for the investigation seeking the appearance and testimony of the ex-husband, according to a press release from Al Watkins.

“The issuance of a Grand Jury subpoena conclusively indicates that the Circuit Attorney’s Office has elevated its undertakings to include Grand Jury proceedings, for which subpoena power and other discovery tools are available,” Al Watkins said in the press release. “The power of subpoena is an invaluable tool to garner evidence and compel testimony which far transcends that which is accorded investigative personnel not otherwise armed with a Grand Jury,” added Watkins.

RELATED: St. Louis Circuit Attorney launching investigation of governor

Grand jury proceedings are confidential in the State of Missouri, requiring even those who testify to keep secret that which they say in Grand Jury proceedings.