Mr. Schaffer said Mr. Paxton’s role in misleading the investors had come to light in an investigation by members of the Texas Ranger Division. Mr. Schaffer and the other special prosecutor, Brian Wice, are Houston defense lawyers appointed by a judge to act, effectively, as district attorneys in the case.

In a statement, Mr. Paxton’s lawyer, Joe Kendall, said the judge in the case has “specifically instructed both parties to refrain from public comment on this matter, and we are honoring the Judge’s instructions.” Before the indictment, a spokesman for Mr. Paxton, Anthony Holm, was outspoken in defending Mr. Paxton. He characterized the case as a political witch hunt, suggested that an anti-Paxton blogger had engaged in jury tampering, and questioned the special prosecutors’ eagerness for news coverage and their impartiality as criminal defense lawyers.

“If society continues to overlook this witches’ brew of jury tampering, media leaks and freshman prosecutors, we may wake up to find the office of the attorney general of Texas at the mercy of two criminal defense attorneys who take checks from the very drug cartel leaders and child molesters the attorney general tries to imprison,” Mr. Holm wrote in an op-ed article in The Austin American-Statesman.

Mr. Schaffer said politics had played no part in the indictment.

“I have nothing personal against Mr. Paxton based on his politics,” he said. “Even if you found fault with Brian Wice or myself, how do you find it with the Texas Rangers? These are the most honest, straightforward, incorruptible police officers you’re ever going to find. They don’t have political motivations, and they certainly wouldn’t have any against the sitting attorney general.”

A conviction for a first-degree felony in Texas can carry a punishment of life in prison or a sentence of five to 99 years. A third-degree felony is punishable with a sentence of two to 10 years. Mr. Paxton helped create the possibility of such severe punishment: As a freshman representative in the Texas House in May 2003, he voted to amend the state securities law to make it a felony to act as an investment adviser representative without being registered, the very crime the grand jury accuses him of committing.