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Death Penalty Expert Witness Condemned by Appeals Court Rulings

Prison investigator A.P. Merillat's court testimony about the violence inmates serving life sentences can inflict has helped send at least 15 murderers to death row. Now, his credibility has been condemned by the state’s highest criminal court.

by Maurice Chammah, The Marshall Project
A.P. Merillat has spent more than 20 years as an investigator of prison crimes and been a go-to expert for prosecutors seeking the death penalty. In June, the courts reversed a second death penalty conviction based on his inaccurate testimony.

A.P. Merillat has spent two decades investigating crimes in Texas prisons, and his testimony about the violence that inmates serving life sentences can inflict has helped send at least 15 murderers to death row.

Now, the credibility of Merillat — a go-to expert for prosecutors seeking the death penalty — has been condemned by the state’s highest criminal court, after judges determined that Merillat gave false testimony and two death sentences were reverted to life sentences, the most recent in June.

Merillat said he was close to being devastated by those decisions. “A guilty capital murderer was removed from the punishment a jury, according to proof beyond a reasonable doubt, determined he deserved,” he said.

Merillat said he believes the court has unfairly jeopardized his standing — and that he is facing an uphill battle to repair it.

“I am currently attempting to rebuild my reputation for honor and integrity that was so unjustifiably destroyed by our own Court of Criminal Appeals,” he said.

Merillat, 56, began his career as a policeman in Huntsville and Houston, and for years, he said, he assumed that anyone who committed a heinous capital murder would be closely watched by the prison.

“I was very mistaken,” he said.

For the last 20 years, Merillat has been an investigator with the Special Prosecution Unit, an independent agency financed by the governor’s office to investigate and prosecute crimes that occur in prison.

“I see the ugliness of the prison system that is not very well known,” Merillat told a Travis County jury last year. “Visitors have been harmed by inmates in the visitation areas. One of our prosecutors was stabbed in the stomach before he got his law degree.”

For a Texas jury to sentence a murderer to death, it must find that he or she will be a continuing threat to society. For decades, prosecutors relied on psychiatrists to testify that the accused would commit violent crimes again if given a sentence less than death.

Many of those psychiatric experts, like James Grigson (popularly known as Dr. Death), Richard Coons and George Denkowski, have since been discredited for their predictions of future dangerousness. Instead, prosecutors have turned to prison experts for testimony about the opportunities for violence behind bars — but outside of death row.

Merillat became popular with Texas prosecutors, publishing training books and winning awards for his seminars. He published a manual for the Texas District and County Attorneys Association called “Future Danger.”

“I got to the point where I was seeing defense lawyers bring in so-called experts for large amounts of money,” Merillat said. “Jurors were hanging their hats on false information.”

James Farren, the longtime Randall County district attorney who called on Merillat in the 2009 retrial of Brent Ray Brewer for a 1990 stabbing and robbery in Amarillo, said he has always found Merillat to be “professional, competent, and very knowledgeable.”

But in 2010, Texas’ Court of Criminal Appeals threw out the death sentence of Adrian Estrada for the 2005 stabbing of 17-year-old Stephanie Sanchez. Judge Barbara Hervey found Merillat erred by testifying that a convicted capital murderer would have more freedom in prison than would ever be possible.

Then, earlier this year, the court threw out the death sentence of Manuel Velez, a death row inmate convicted of killing his girlfriend’s infant son, after his attorneys found Merillat had given similar testimony in his Cameron County trial.

Brian Stull of the American Civil Liberties Union, who represents Velez, said Merillat’s voice and personality led jurors to “trust him right away.”

“He gives the jury great stories, and the jury becomes part of the story,” Stull said, “because the jury can help stop violence that is rampant in Texas prisons.”

“It makes me worry about everything he says,” Stull added.

Among defense attorneys and their expert witnesses, Merillat has long been distrusted.

“His testimony was always anecdotal,” said Larry Fitzgerald, a former spokesman for the Texas Department of Criminal Justice who has testified in more than 30 cases for the defense, several times across from Merillat. “I always felt safe when I walked into these [prison] units, but if you listen to A.P’s testimony, it’s like blood flowing down the aisles."

While defense attorneys search to see if Merillat has made similar statements in past cases, prosecutors too will be on the hunt — for other experts on the prison system. Farren said he used Merillat's former boss in past cases, and will continue to seek out other investigators. 

Merillat, for his part, said he'd "be a fool" to get back on the witness stand. 

“Even a first-year defense lawyer would certainly be shrewd enough to begin cross-examination of me with, ‘You have been determined by … the highest court in the state to be a liar, haven’t you?’"

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