Dallas man caught on camera kidnapping 4-year-old before his murder could use insanity defense

The man caught on camera taking a 4-year-old Dallas boy from his bed and killing him nearly four years ago is now competent to stand trial. FOX 4 is learning more about what that means and how his capital murder case could proceed.

4-year-old Cash Gernon murdered

The backstory:

It was a sad scene in May of 2021 when a jogger found the body of 4-year-old Cash Gernon on Saddleridge Drive in South Dallas.

He’d been stabbed to death.

"The sweetest little boy. He loved everybody," Cameron Mori told FOX 4 in a 2021 interview.

Mori’s mom had been taking care of Cash and his twin brother. She was friends with their father, who left them with her. Their mother was not around.

Dallas police arrested Darriynn Brown, who was 18 at the time, and charged him with burglary, kidnapping, injury to a child, and capital murder.

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Camera shows 18-year-old taking Dallas 4-year-old from his bed hours before his death

An arrest affidavit says a baby video monitoring system showed Darriynn Brown, 18, taking Cash Gernon, 4, from his bed just hours before the child's body was found in a southwest Dallas street.

An arrest affidavit said a baby monitor captured video of Brown taking Cash out of his bed while he was sleeping.

DNA evidence also linked Brown to the little boy’s murder.

But both prosecutors and defense experts agreed that he was incompetent, and he was sent to the Terrell State Hospital.

Darriynn Brown’s competency restored

Darriynn Brown (2025) (Dallas County jail)

What we know:

Last week, Brown was returned to the Dallas County jail after being declared competent to stand trial. That means he’s undergone treatment and is now able to understand what he is on trial for.

What we don't know:

Defense attorney Heath Harris said there are still questions about his client’s mental state at the time of the crime.

"It’s not about what his current mental state is. It’s what was his mental state at the time of this alleged offense. We said then and we are saying now that we believe the insanity defense will come into play," Harris said.

Related

Man accused of murdering Dallas 4-year-old Cash Gernon now competent to stand trial

The man accused of kidnapping a Dallas 4-year-old from his bed and murdering him is now competent to stand trial, a judge declared.

What they're saying:

"For the insanity issue, it’s whether you were legally insane at the time of the crime," said former prosecutor Toby Shook, who is not involved in the case.

Shook believes prosecutors will hire their own experts to try to assess Brown’s mental state when Cash was killed.

"What the DA’s office has done in the past, if they believe once their experts look at it that there is a true insanity defense, often times they agree. Now, that doesn’t mean the defendant gets off and goes home by any means. But they’ll agree. If the DA’s experts don’t agree, then there usually is a trial and there will be a battle of experts," he said. 

What's next:

Prosecutors will review Brown’s treatment records and likely administer more psychological tests to determine how to move forward with the case.

Judge Stephanie Huff is presiding over the case and is reportedly trying to expedite the trial.

Harris said that while Brown is competent now, he may not be by the time the trial begins, if it gets that far.

"He’s dealing with a mental illness, a mental disease," he said.

The Source: The information in this story comes from interviews with defense attorney Heath Harris, former prosecutor Toby Shook, and past news coverage.

DallasCrime and Public Safety