Justice Unraveled: How flawed forensics will impact high-profile cases

Some will get a second chance, most won't

AUSTIN (KXAN) -- By the evening of Sept. 9, 1998, Louis Castro Perez’s feet were raw from wandering barefoot down South Austin streets. He was scratched, bleeding and disheveled, and he needed a place to sleep.

Perez, 36 at the time, was in shock. He’d just spent a leisurely day with a new acquaintance, a California drug dealer. The pair went to Zilker Park. They watched girls play volleyball in the sun. They snorted cocaine. They drank into the late afternoon.

Then Perez returned to the home of his ex-girlfriend, Michelle Fulwiler, where the two had partied the previous night into the early morning.

He took off his socks and shoes outside, opened the front door and stepped into a horror scene. Blood splattered the walls. Fulwiler’s housemate, 38-year-old Cinda Barz, lay on her back in the front hallway, a pool of blood spread beneath her.

From left to right: Michelle Fulwiler, Cinda Barz, Staci Mitchell
From left to right: Michelle Fulwiler, Cinda Barz, Staci Mitchell

Perez knelt by Barz’s side. She gasped for air and scratched at his face and neck.

“It was so awful and so fast that it scared the hell out of me,” Perez said.

Perez fled. He didn’t know two more murder victims lay strangled and beaten in back bedrooms.

That is, at least, the story Perez told a jury in 1999.

Without eyewitnesses, prosecutors emphasized so-called DNA mixture evidence to make their case. A Travis County jury found Perez guilty and sentenced him to death Sept. 25, 1999.

But now, 17 years later, scientific advances are calling into question the accuracy of DNA mixture calculations.

The case against Perez, who has steadfastly maintained his innocence, may yet be undermined.

And he is far from alone.

Thousands in limbo

The revelation that decades of DNA evidence could be skewed has set off a monumental, statewide scramble by the Texas criminal justice community to address the alarming reality: flawed science may have sent untold numbers of innocent people to prison. 

Tens of thousands of cases across Texas could potentially be reviewed to make sure flawed DNA analysis did not play a key role at trial.

The issue can be traced back to May 2015, when the FBI found minor discrepancies in population data it used to calculate DNA match statistics. Some prosecutors asked for statistics to be recalculated. They were not expecting significant changes.

A whole new problem surfaced, according to a report by the Texas Forensic Science Commission, which has helped guide the ballooning effort to confront this DNA calculation debacle.

In some cases, the recalculations vastly altered the odds that individuals matched DNA found in mixtures, which include two or more contributors.

“In one case in Galveston County, the stats changed from 1 in 1.4 billion to 1 in 38. In another, the stats changed from 1 in 1,000 to inconclusive,” according to a summary evaluation by the DNA Mixture Review Project.

KXAN DNA TimelineIt appeared all DNA mixture analyses done before 2010 could need recalculation. That year, a scientific working group made recommendations to upgrade mixture-testing protocol.

Members of the criminal justice community, such as Bob Wicoff, began taking action.

Wicoff heads the DNA Mixture Review Project, and he is the chief of the appellate division of the Harris County Public Defender’s Office. With funding from a Texas Indigent Defense Commission grant, the project is now combing through thousands of cases to single out ones in which DNA mixtures played a vital role and substantially impacted the verdict.

“Our review is focused on finding wrongful convictions, and motivated by the concern that someone who has been wrongfully convicted through flawed DNA testing may be waiting to have his case reviewed,” Wicoff said in an email.

Out of the tens of thousands of cases that may ultimately be reviewed, Wicoff said he expects just a fraction will be found to have been fundamentally impacted by faulty DNA analysis. The goal is to prioritize cases and focus first on individuals with the highest chance of finding case-altering results upon recalculation.

As of mid-October, the project had received requests to review roughly 950 cases. It had gotten through about 400, and it had requested recalculations in about 10 percent of those cases.

The project is working with about 50 Texas prosecutors’ offices to flag cases in need of review.

KXAN asked Wicoff: Is it likely innocent people were convicted based on the flawed science?

“Given the large number of cases involved, I would think so,” he responded.

The root of the problem, said Scott Henson, a Texas criminal justice expert and former executive director of the Innocence Project of Texas, is that most technicians performing DNA mixture analysis did not fully understand the complicated mathematics behind the process.

Experts still do not know the full scope of the problem and how many people may be affected by this, Henson said.

“We are seeing the growing pains, as science is being applied to law enforcement, and it is going to be really messy,” Henson said. “It is going to be expensive to fix.”

Henson said he anticipates many of those people wrongfully convicted with flawed DNA evidence will never receive compensation.

“Many they’ll just never find,” Henson said.

The Travis County District Attorney’s office is one of a handful of DA offices in Texas sending out notices itself.

In Travis County alone, the DA’s office has flagged almost 1,400 cases dating back 15 years in which DNA evidence may need recalculation. The office has sent more than 1,000 so-called Brady notices to defendants.

“I’m writing to notify you that the above criminal case might possibly be impacted by recent scientific developments relating to DNA evidence,” the form letter reads.

A Brady disclosure relates to evidence that must be released to a defendant because it proves innocence. The “scientific developments” could relate to mixture testing or the use of FBI’s database, said the Travis County DA’s office.

KXAN found more than 40 murder, rape and aggravated assault cases from Travis County in which the defendants received the same Brady notice. Unfortunately, cases out of Travis County cannot be recalcuated out of APD's lab due to the abrupt closure following a scathing audit by the Texas Forensics Science Commission.

One of those notices went to Perez. At his trial, Travis County prosecutor Claire Dawson-Brown likened the DNA evidence to bricks.

“These are the bricks in the wall, this wall of evidence that is encircling him,” Dawson-Brown said in her closing remarks. “He cannot escape from it.”

‘Nail in the coffin’

Police did not arrest Perez until days after the killings. They found him at a convenience store payphone. He said he was talking to a lawyer and arranging to turn himself into police.

The fact that Perez had fled the scene without calling police, that he told conflicting stories about the origin of the scratches on his neck and face, that his shoes and socks were missing, that the California drug dealer who could corroborate his alibi disappeared without a trace, among numerous other pieces of circumstantial evidence, played into the prosecution’s case against Perez.

But to tie Perez to the murders in the back of the house, prosecutors leaned heavily on DNA mixtures.

Police had found Perez’s ex-girlfriend, Fulwiler, wrapped in a comforter in the master bedroom. She had defensive wounds on her hands, strangulation marks on her neck and blunt-force trauma to her head. Underneath her fingernails, investigators found DNA mixtures.

She gasped for air and scratched at his face and neck.

Cinda Barz’s 9-year-old daughter, Staci Mitchell, was found shirtless, kneeling at her bedside. Her arm was lashed to a bedpost with pantyhose. She was strangled. Her face and head had been beaten. Mitchell’s fingernails yielded DNA mixture evidence, too.

In addition, investigators found multiple people’s DNA on a towel found wrapped around the handle of a knife resting on top of Mitchell’s homework at a table. A piece of the same towel was found on the ground by Barz’s body.

But Perez was friendly with the three victims. He was seen drinking at the home by an independent witness the night before the killings. As his defense attorney said at trial, there were innocent ways he could have left traces of DNA throughout the home, including under the victims’ fingernails.

In court, prosecutors said DNA under Barz’s fingernails could not exclude Perez, and 1 in 2,330 Hispanics would match it. Neither could Perez be excluded as the contributor of the DNA under Mitchell’s fingernails. One in 14 Hispanics would match it, Dawson-Brown said.

Perez could not be excluded as a contributor of DNA found on the towel, either, according to trial testimony.

“It’s the cumulative effect of all this evidence. They’re not just a lot of random coincidences that his DNA is on the towel, that his DNA is under Cinda’s nails, that DNA that matches him and does not exclude him is under Staci’s,” Dawson said in her closing remarks. “Are those all coincidences?”

Prosecutors repeatedly hammered the importance of DNA. And jurors, said Travis County Senior District Judge Jon Wisser, have mostly accepted DNA evidence up to this point. In the case of Perez, if further DNA testing shows another person’s DNA, it could be enough to question the verdict, he added.

Wisser presided over Perez’s 1999 trial. He spoke with KXAN in October.

“[Perez] was convicted very heavily based on DNA evidence,” Wisser said. “The DNA is sometimes the coffin nail.”

Old wounds

In September, Meyer told KXAN that proving her brother’s innocence has been at the center of her existence for the past 16 years.

She keeps a framed photo of Perez near the center of her kitchen table.

Louis Perez is on Texas Death Row (Perez Family Photo)
Louis Perez is on Texas Death Row (Perez Family Photo)

“I have never thrown away a shred of evidence that I thought may help my brother some day,” Meyer said.

Perez’s attorney filed to have DNA in his case recalculated. Perez initially agreed to a death-row interview, but his attorney advised him against it.

If reopened, Perez’s case is sure to aggravate old wounds. The murders had a deep impact on each victim’s family. At one point during the trial, Staci Mitchell’s father, Joe Mitchell, screamed and lunged at Perez.

Perez’ case is one amid thousands, each with its own constellation of heartbroken siblings and parents. All of them may now be questioning the validity of DNA evidence used for convictions.

They may have to relive not only the memory of the crime, but, possibly, also another trial.

As Dawson-Brown said shortly before the jury sentenced Perez to death: “The shockwaves that have gone out throughout those families is going to be left for an eternity.”

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