LASD used defective DNA test kits for 8 months, retesting thousands of samples

LOS ANGELES - The Los Angeles County Sheriff's Department announced that it has been using potentially faulty DNA test kits for months after discovering a months-old notice from the DNA test kit company saying the tests may be defective. Now, the department is working to retest thousands of samples. 

Defective DNA test kits

The backstory:

In a press release on Wednesday, the department said deputies found out about the kits this week, despite the company reaching out to the department in August. 

The notice from the company recommended that the department discontinue the kits, because a specific lot was "prone to intermittently poor performance with potential to cause incomplete results or profiles."

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So why did it take months for the department to stop using them? According to the LASD, the company's letter was forwarded to someone who wasn't with the department anymore.

Because of the mix-up, the department used the faulty kits for about eight months, from July 2024 through February 2025, the LASD said Wednesday.

Retesting DNA samples

Why you should care:

Officials are still working to figure out just how many cases were impacted by the faulty kits, and to what degree, adding that the problem affects other law enforcement agencies and the LA County District Attorney's Office. But, the department said that the tests. The test kits, the department said, could have returned incomplete results, but called it "not likely" that the faulty test kits would have falsely identified someone. 

Now, the LASD's Scientific Services Bureau will retest thousands of samples to figure out just how bad the problem is, but added that some samples couldn't be retested because their sample sizes were too small.

Departmental investigation

What they're saying:

The LASD said that it will be reevaluating its policies and quality assurance measures for scientific testing. 

"We take the integrity of our criminal investigations and the reliability of our forensic testing very seriously," LA County Sheriff Robert Luna said, adding that the department is "taking immediate corrective action to protect the accuracy of ongoing and future cases."

LA County DA Nathan Hochman said that his office is working with the LASD to figure out how many people and cases are affected.

"There is no concealing this. Just the opposite. We're going to determine each and every case in which a faulty DNA sample may have been used. Alert defense counsel in appropriate cases where DNA material still exists, retest that sample," Hochman said on Thursday, March 28.

What we don't know:

It wasn't immediately clear what company produced the faulty test kits.