A grieving Florida mother celebrated a 30-year prison sentence for the man who sold her daughter a fatal dose of fentanyl in 2021 — in a case that highlights the state's zero-tolerance policy in combating the opioid crisis.

"The fentanyl coming into our country is a tidal wave," Jacksonville State Attorney Melissa Nelson told Fox News Digital of the drug that can be 50 times more potent than heroin. "This is our opportunity to incapacitate dealers who are killing people." 

Patricia Brantley found her daughter, Leigh Brantley, 39, in her bed with her hand resting on the back of her beloved black lab, Coal, on May 4, 2021. She was dead.

"Coal was at her side constantly," Patricia Brantley said of the service dog. "It gives me some comfort knowing that she was stroking him and rubbing his back when she finally took her last breath."

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A side by side of Leigh Brantley in a baseball cap and her drug dealer Derrick Smith

Leigh Brantley as a teenager (left) died May 4, 2022, of a fentanyl overdose in Jacksonville, Florida, and her drug dealer, Derrick Smith, was convicted of manslaughter and sentenced to 30 years in prison for her death. (Courtesy of Patricia Brantley/ Florida Department of Corrections)

In February, a jury convicted Derrick Smith, 51, of manslaughter, conspiracy to sell drugs and unlawful use of a communications device for selling Leigh the deadly concoction. 

Due to a change in Florida law, prosecutors can more easily bring murder and manslaughter charges against drug dealers in fentanyl overdose deaths.

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Florida has had drug-induced homicide laws on the books since 1982, but fentanyl was only added to the list of drugs that qualify in 2017.

In the wake of the fentanyl-driven opioid crisis, many states have passed new laws that subject drug dealers to first-degree murder and manslaughter charges for overdose deaths.

A photo combination of Leigh Brantley smiling and her service dog, Coal

A photo combination of Leigh Brantley in Honduras on a mission trip for a dental ministry (right), and her beloved black Lab, Coal, who was at her side when died of a drug overdose. (Courtesy of Patricia Brantley )

In 2021, more than 107,000 people in America died of drug overdoses, mostly from fentanyl — the highest number ever recorded and more than the number of people who perished from car crashes and gunshot wounds combined, according to publicly available statistics.

Smith’s manslaughter case was the first to go to trial in Jacksonville, the fourth-largest metro area in Florida.

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Joe Licandro, the lead assistant district attorney in the office’s Narcotics Homicide Overdose Team, told Fox News Digital that the change in the law has lessened the burden on prosecutors. 

Now, prosecutors have to prove that fentanyl contributed to an overdose death, whereas before they had show it was the exclusive cause — a tricky bar when a person has more than one drug in their system.

Headshot of Melissa Nelson posing beside an America flag

Jacksonville State Attorney Melissa Nelson, whose office is aggressively prosecuting drug dealers for overdose deaths. (Jacksonville State Attorney's Office )

"It’s our goal in these cases to try to go up the chain as much as we can and use our authority to get the big dealers," he said. "That’s how we’re trying to choke off the supply chain."

The Jacksonville State Attorney’s Office has prosecuted 113 drug dealers for murder and manslaughter since the new law took effect. The office has obtained 52 convictions — 20 of which are for murder. There are 61 cases still pending. 

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Licandro, who prosecuted Smith, said that in these cases, the victims' cellphones are key pieces of evidence.

Investigators identified Smith from text messages they found on Leigh Brantley’s cellphone, which showed she first met him at a local gas station two weeks before her death. On the day she died, she bought $20 worth of fentanyl from him.

Leigh Brantley standing beside a large Mayan sculpture

Leigh Brantley visiting Mayan ruins on a trip to Mexico. (Courtesy of Patricia Brantley)

The Florida State College graduate had worked as a surgical technician at a tissue bank helping harvest body parts for research before her struggle with addiction hijacked her life. 

For nearly two decades, she was in and out of rehab facilities trying to get sober.

After her last stint in rehab in 2021, she’d asked her mom for help. "She wanted to get her life back, she wanted to start working again," said Patricia Brantley. "She was trying."

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Nelson, the Jacksonville state attorney, said that aggressive prosecution of drug dealers is a tool and a deterrent, not a solution. "We are never going to arrest our way out of this problem," she said. 

Fentanyl killed 5,302 Floridians in 2020 and overdose deaths were up another 9% for the first half of 2021, according to the most recent data available from the Florida Department of Law Enforcement. 

teenage Leigh Brantley

A teenage Leigh Brantley at her mother's house. (Courtesy of Patricia Brantley)

Most of the fentanyl in the U.S. originates in China and is trafficked in from Mexico across the southern border, where seizures of the drug are up 200% in the last four years, according to federal authorities. 

But every year, greater quantities of the deadly and illicit narcotic are flowing into U.S. cities towns. Florida officials announced last month that they had seized 8.35 kilograms of fentanyl in a drug bust, enough to kill 4 million people.

An analysis from Fair and Just Prosecution, a national alliance of progressive prosecutors, said that drug-induced homicide prosecutions don’t reduce overdose deaths and may actually increase them. 

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"Often the greatest barrier to urgent medical attention [in overdoses] is fear of arrest and prosecution," says the nonprofit's report, which called the severe punishments for drug dealers "inhumane."

These laws unfairly target low-level dealers and the friends and family of overdose victims rather than kingpins or large-scale sellers, according to the Drug Policy Alliance, a nonprofit that advocates for decriminalization of illegal drugs.

But Patricia Brantley said Smith got exactly what he deserved. "How many other people has he killed?" She asked. "I don’t feel that the sentence was harsh."

She said she will never recover from losing her daughter. "I don’t think there is an hour I don’t stop and think about her," she told Fox News Digital. "I used to go home to her everyday — and now I go home to an empty house." 

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Leigh Brantley added a bible study app to her mom’s cellphone, and a verse still pops up several times a day.  

"I won’t take them off my phone because I know it’s Leigh talking to me," she said.