A Houston lawyer, for reasons unknown, is trying to get the detailed billing records submitted by special prosecutors pursuing felony charges against former Gov. Rick Perry, opening another front in the tangled legal saga.

While the likely presidential candidate waits to hear if an appeals court will throw out the charges against him, special prosecutors Mike McCrum and David Gonzalez are now suing state Attorney General Ken Paxton on the side. They are fighting an open records ruling that might force them to disclose details of their investigation, including whom they have interviewed while building their case against Perry.

This new sidebar in the Perry case began on Dec. 17 when Houston lawyer Trevor Sharon filed a public records request with Travis County court officials asking, among other things, for copies of all invoices prosecutors have submitted in the case. (Because of various conflicts, McCrum was brought in as special prosecutor, and bills the county for his work.)

Why does Sharon want the records? Repeated calls and emails sent to Sharon by the Tribune received no responses. He is listed as an associate with Paul Doyle & Associates in Houston.

On March 12, Paxton's office ruled that the invoices are public records, and must be released.

"Attorney General Paxton’s decision is unprecedented," McCrum said in a statement to The Texas Tribune. "The Attorney General is telling us we must disclose the detailed work described in our billing statements, such as who I talked to and when, or what documents I reviewed."

McCrum added that he and his co-counsel have agreed to disclose how many hours they worked by categories like interviews, legal research and court appearances. But he argues that disclosing details that would reveal witnesses' names is "unprecedented."

In a suit filed against Paxton on March 26 Gonzalez — a second special prosecutor brought in to help McCrum - argues that the invoices are part of a judicial record, not a "governmental" one and therefore not subject to the state's public records law.

The special prosecutor's lawsuit points to 552.108 of the Public Information Act which states that information "held by a law enforcement agency or prosecutor that deals with the detection, investigation or prosecution of a crime is excepted" from disclosure if it interferes with the investigation or prosecution of a crime.

Perry was indicted on Aug. 15 for allegedly abusing the power of his office by threatening to veto funding for the state’s public integrity unit unless Travis County District Attorney Rosemary Lehmberg, who had pleaded guilty to drunken driving, resigned. The public integrity unit, which is charged with investigating and prosecuting state corruption, is housed within the Travis County district attorney's office. Lehmberg, a Democrat, refused to step down. Perry later made good on his threat, vetoing the approximately $3.7 million per year budgeted to fund the unit.

Currently, the Perry legal team has challenged the indictment on two fronts. There's a request before Judge Bert Richardson to quash an amended indictment filed by the prosecutors. There's also an appeal of Richardson's ruling to let the case proceed before the 3rd Court of Appeals.

As for Sharon, he does not work for the Perry legal counsel, according to Tony Buzbee, who leads the potential presidential candidate's defense team.

Buzbee said he did not know Sharon. "He has nothing to do with the Perry case at all," Buzbee said.

Disclosure: Tony Buzbee was a major donor to The Texas Tribune in 2012. A complete list of Tribune donors and sponsors can be viewed here.