The Houston school district has enlisted the assistance of the Harris County District Attorney's Office to combat educator-led test cheating after struggling in recent years to oust teachers accused of helping students pass the high-stakes exams.

Superintendent Terry Grier said he met with District Attorney Devon Anderson late last week to discuss how her office could help, possibly using its power to issue subpoenas to compel testimony against educators cheating the system to benefit themselves financially.

"It's very, very difficult to prove a person was involved in cheating," Grier said. "The teachers stand to earn significant amounts of money by helping kids cheat."

HISD teachers and administrators can earn thousands of dollars in bonuses for improving scores on the annual State of Texas Assessments of Academic Readiness exams that students at some grade levels must pass to move to the next grade level or graduate. This year, the district distributed $18 million in bonuses, with teachers whose students made the biggest gains eligible for up to $10,000. Grier also has earned bonuses based partly on test data.

"Our public integrity division will be looking at any case they bring to us and will assist in any way we can," said Jeff McShan, spokesman for the District Attorney's Office.

The informal local agreement comes as one of the nation's largest academic cheating scandals is playing out in an Atlanta courtroom, with a dozen educators standing trial. About 20 others pleaded guilty after a state investigation, ordered by the Georgia governor, that involved more than 800,000 documents and 2,000 interviews.

The Houston school district's last two cheating investigations at Jefferson and Atherton elementary schools - which cost a combined $497,444 - ended recently with seven teachers resigning and each receiving one year's salary as part of settlement agreements; another teacher resigned for a job elsewhere prior to HISD offering the deal.

Summary reports of the investigations said several students confessed that their teachers offered improper help. At Jefferson, 100 percent of the third-graders passed the English-language STAAR exams in reading and math in 2013, flawless performance matched only by HISD's gifted school, T.H. Rogers, according to district data. Atherton's gains - of 20 to 30 percentage points - far surpassed the district's norm.

Trying to verify test cheating can be a lengthy, pricey puzzle, and appeals afforded public schools educators add to the time and expense. Statistical models can pinpoint highly unlikely test scores, and a review of test materials can show suspicious erasure marks. But confessions are rare, and students, particularly young ones, aren't always ideal witnesses.

The president of the teachers' union and attorneys for the teachers from Atherton and Jefferson said the educators did nothing wrong and blasted the district's investigations, conducted by a local law firm.

"We're talking about something that's so high-stakes," said James Wollack, associate professor of educational psychology at the University of Wisconsin who studies test security and statistical methods to detect cheating. "When companies or an auditing firm is conducting these analyses, folks should be using methods that have been evaluated by the research community."

Private law firms

After taking the helm of the Houston Independent School District in 2009, Grier hired private law firms to investigate cheating allegations instead of using internal investigators. The district's research department does some of the data analysis, and the Texas Education Agency, at Grier's request, has reviewed testing materials for high rates of erasure marks.

Grier said he does not suspect widespread cheating such as what occurred in Atlanta. Rather, HISD has reported a handful of cheating cases every couple of years.

One of the Jefferson teachers recently cleared of cheating, Elsa Rodriguez, is suing the law firm of Martin, Disiere, Jefferson & Wisdom, which conducted the investigation for HISD. According to the lawsuit, Rodriguez was on medical leave during the testing - "a fact they could have verified with a phone call."

Larry Watts, the attorney representing Rodriguez, also has sued HISD in state and federal court on behalf of employees from Key Middle School implicated in a 2010 cheating investigation done by the same law firm. U.S. District Judge Ewing Werlein Jr. has dismissed most of the claims in the federal Key case.

A representative of the Martin, Disiere firm could not be reached Friday.

In the Key case, one of the teachers, Adedayo "Richard" Adebayo, had his teaching certificate revoked by the State Board for Educator Certification in 2012, records show.

Adebayo also was accused in 2005 of cheating under the same Key principal, Mable Caleb. Former HISD Superintendent Abelardo Saavedra tried to demote Caleb, but the school board voted 4-3 to reinstate her.

Caleb, who has repeatedly denied wrongdoing, was implicated during Grier's 2010 investigation. The Texas Education Agency tried to revoke Caleb's certification, but in 2013 Administrative Law Judge Joanne Summerhays ruled there was insufficient evidence that Caleb was aware of any breach in test security.

Chris Tritico, Caleb's attorney, who recently represented the Jefferson teachers who resigned with a year's pay, said the outcomes vindicate the educators.

"In both of these cases," Tritico said, "I think there was a rush to judgment and not a full investigation of the facts."

Tritico said he thinks cheating investigations by the District Attorney's Office likely would be more fair than HISD's prior inquiries.

"But to turn an administrative matter into a criminal matter because you don't want to spend the money to do the investigation right is not in the best interest of the public or your employees," he said.

No full reports

HISD has released summaries and some exhibits from the Atherton and Jefferson investigations, but the district has refused to provide the full reports despite having done so in the past. The district successfully argued to Texas Attorney General Greg Abbott's office that the two reports constitute teachers' evaluations, which are confidential under state law.

In some cases, accusations of cheating against a teacher may never be known to parents or to other schools looking to hire the person. School districts are required to report testing violations to the Texas Education Agency, and online state certification records show whether a teacher has been sanctioned but provide no description of the reason.

Since 2003, the State Board for Education Certification has sanctioned 119 teachers - nine a year on average - for testing violations, including directly or indirectly providing students with improper help.

HISD spokeswoman Sheleah Reed, asked if HISD would tell another district that a former employee had been the subject of a cheating investigation, said only that the human resources staff verifies basic information like position held and dates of employment.