ACOLD CASE, ADNA HIT AND FINALLY JUSTICE... OR WAS IT?

The murder of Claire Penelope Hough wasthe kind of mystery that keeps homicide detectives awake at night pulling at loose threads.

For almost 30 years, they’d tugged and tugged andcouldn’t unravel t. Now they wanted to try again.

Their persistence was due partly to Hough’s age a month shy of 15 when she was sexually assaulted and strangled on an August night in 1984. Cops have teenage daughters, too.

Part of it was the savageryof the attack at Torrey Pines State Beach She was battered in the face and slashed on the neck Sand was stuffed down her throat. Her left breast was cut off

So yes, they wanted to catch this monster, even as the years ticking by made that more difficult Time is no ally to crime-solvers: evidence degrades, witnesses die detectives get assigned to other cases.

But as the calendar advanced so did science.

Every couple of years, new techniques or equipment would come along, offering hope to cold-case detectives working unsolved murders. They would retrieve old items stored in evidence rooms and ask the forensic scientists to have another go

So it was in the summer of 2012 that Lynn Rydalch, a San Diego Police Department homicide detective, sent an email about the Hough murder to the department’s lab.

“I don’t want to leave any stone unturned,” he wrote. “Any ideas you have for something that might have been missed would be greatly appreciated.

The request went to criminalist David Cornacchia He’s an expert in DNA, the increasingly sophisticated identification of criminal suspects from even the tiniest bits of blood, saliva and other bodily fluids.

Since its introduction in the late 1980s, it has revolutionized crime-solving, considered so irrefutable as evidence that it spawned a maxim: “DNA don’t lie.”

Earlier tests done over the years on clothing and other evidence located stains that appeared to be from humans.

But the lab never had enough material to link it to anybody

This time, using more powerful tools, Cornacchia extracted DNA, amplified it, and created a genetic profile. He ran it through law-enforcement databases to see if there was a match.

In Hollywood movies television cop dramas and true-crime podcasts, th s is the swelling moment of delicious truth.

Lady Justice rebalances her scales and reaches across the decades to tap a bad guy on the shoulder Sometimes she taps in real life, too.

Blood spots on Hough’s jeans and underwear came back to a felon named Ronald Tatro.

His criminal record included raping a woman at knifepoint in Arkansas in 1974 and attempting to kidnap a teenager in La Mesa in 1985 after zapping her twice with a stun gun. He once checked himself into a psychiatric clinic, troubled by his inability to control violent urges.

Finally it seemed, the planets had aligned to solve Claire Hough’s 28-yearold murder But there was a complication. Cornacchia also got a DNA hit on vaginal swabs collected all those years ago during the girl’s autopsy And it wasn’t Tatro. The sperm cells belonged to someone familiar to the crime lab. He used to work there.

Kevin Brown grew up in Sacramento, the youngest of two children. His father was a podiatrist his mother an administrative assistant in state government. He went to Cal State Sacramento and got a bachelor’s degree in forensic science. After he graduated, in 1979, he started working as a criminalist for the New Mexico state police. Brown liked the job but not the location. He was a Californian at heart Three years in, he moved to the San Diego police lab. He stayed for 20 years, rotating through various units narcotics, firearms, serology, trace evidence before leaving in 2002.

Adecade later his DNA showed up in the Hough case. And it stunned the police lab. Manager Jennifer Shen and other supervisors huddled behind closed doors, trying to figure out what the result meant and what to do about it. Shen knew Brown. They had been in the same lab for seven years at the beginning of her time there and the end of his. She remembered him as “a very pleasant person” and had enjoyed their office interactions.

It was upsetting to think that one of their own could be a murderer especially someone who was by all accounts mild-mannered, even timid. Brown was 6-foot-4 but not imposing.

He was someone whose bosses dinged him in evaluations for getting rattled and tongue-tied during courtroom testimony One female criminalist considered him “weak-jellied” and said, “I could beat the crap out of him myself.” understood how it could theory.

But if Brown didn’t have it in him to assault Hough, that meant his DNA wound up in the evidence through contamination, a prospect that presented its own worries to lab management. It would make them look bad, raise questions about the integrity of the work there.

Inadvertent contamination happens with surprising regularity in crime labs. Technicians brush up against a bicycle or cough over a handgun and their DNA winds up in the mix. They pick up a pen used by someone else, and transfer that person’s DNA onto apiece of evidence down the line.

That’s why Brown and other criminalists provide genet c samples for the lawenforcement database, to weed out mistakes when they happen.

But Brown’s DNA in the Hough case wasn’t from wandering skin cells or droplets of saliva. It was sperm, on vaginal swabs. Lab managers had never encountered such a thing.