(Reuters) - An aggressive legal strategy pursued by U.S. women’s healthcare provider Planned Parenthood may have been critical in turning the tables on opponents who were seeking to prosecute it in Texas for allegedly profiting from sales of aborted fetal tissue.

A sign is pictured at the entrance to a Planned Parenthood building in New York August 31, 2015. Picture taken August 31, 2015. REUTERS/Lucas Jackson

In a surprise move disclosed on Monday, a grand jury in Harris County not only cleared Planned Parenthood’s Gulf Coast affiliate but also indicted the two anti-abortion activists, David Daleiden and Sandra Merritt, who had prompted the probe in the first place.

They have both been charged with using fake driver’s licenses and Daleiden for violating Texas’ prohibition on the purchase and sale of human organs - the same law he accused Planned Parenthood of breaking - when he sent an email to Planned Parenthood seeking to buy fetal tissue. Their lawyers say they have done nothing wrong.

Planned Parenthood’s legal strategy was in some ways similar to how corporations facing major white-collar criminal investigations often cooperate closely with prosecutors to try to influence the outcome.

From the start, Planned Parenthood and its Houston lawyer Josh Schaffer settled on a strategy of cooperating with investigators, said Rochelle Tafolla, a spokeswoman for the affiliate. It included volunteering documents and encouraging prosecutors to interview employees, as well as giving prosecutors tours of the Houston facility, according to Schaffer.

“We certainly began the process as suspects of a crime, and the tables got turned and we ended up victims of a crime,” Schaffer told Reuters in an interview.

Schaffer was retained by Planned Parenthood last summer when Texas officials demanded it face a criminal investigation after the anti-abortion activists posted videos online purporting to show the organization’s employees discussing the sale of aborted fetal tissue, which is illegal in the United States if done for a profit.

The videos produced by Daleiden’s Center for Medical Progress were secretly filmed at Planned Parenthood clinics, such as its Houston facility, and including at least one conversation in a restaurant. Planned Parenthood said it has done nothing wrong and commissioned an outside study that said the videos had been deceptively edited.

According to Planned Parenthood, officials have cleared it of wrongdoing in 12 U.S. states in the wake of the allegations.

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STARTED A DIALOGUE

Schaffer said very soon after he was hired he began a dialogue with prosecutors in Harris County, which includes much of Houston, about the details of the case, and kept that going throughout.

The office of Harris County District Attorney Devon Anderson declined an interview request. Anderson said in a statement on Monday: “All the evidence uncovered in the course of this investigation was presented to the grand jury. I respect their decision on this difficult case.”

A Republican who has been the Houston area’s prosecutor since 2013, Anderson last summer pledged a “thorough investigation” and a prosecution to the full extent of the law “should we find that laws were broken.” Campaign material from her 2014 race for district attorney described her as a “proud, pro-life Texan mother of two.”

Although what happened during the grand jury’s secret deliberations may never be known, Schaffer said it did not vote on whether to indict Planned Parenthood.

That is because the grand jury’s focus shifted to a case against the anti-abortion campaigners, Schaffer said on a conference call with reporters, citing information he said he received from a prosecutor.

Planned Parenthood said that Daleiden and Merritt used fake driver’s licenses in April 2015 when they posed as executives from a fictitious company to secretly film conversations at the Houston facility. That led to the charges they used fake government documents with the intent to defraud.

One critical juncture in the case may have occurred when Planned Parenthood gave law enforcement an important tip: Merritt’s true name, according to Schaffer.

Her identity remained unknown from the time she visited Planned Parenthood with a fake California driver’s license until about December when Daleiden revealed it during a deposition as part of a separate civil lawsuit in state court in Los Angeles, Schaffer said.

As part of his strategy, Schaffer said he explicitly pushed prosecutors to charge Daleiden and Merritt.

“I made the argument regarding the charges that the grand jury returned,” Schaffer said in the interview, “but I did not have to make them very forcefully because it was self-evident to the prosecutors that they engaged in this conduct.”

PROTECTING SOURCES

Peter Breen, a lawyer on Daleiden’s defense team, said the grand jury misapplied Texas law, indicting the two under an anti-fraud statute meant to be used against identity thieves, not against people trying to uncover wrongdoing.

Terry Yates, a Houston lawyer representing Merritt and Daleiden, told reporters the grand jury’s indictments “are legally and factually insufficient and are not going to hold up under the weight of the law.”

Daleiden, who says he uses journalistic techniques, could not have cooperated with Texas authorities’ as extensively as Planned Parenthood without surrendering his rights as an investigator, Breen said. He needed to protect his sources and methods, including Merritt’s name, and he posted what relevant information he had online, the attorney said.

“Numerous law enforcement and legislative bodies across the country have reached out to David,” Breen said. “He has done everything he can to cooperate with their investigations.”

Breen said he did not want to speculate as to why an investigation that began focused on Planned Parenthood suddenly turned on its accusers instead, but he said the district attorney should use her authority to drop the charges.