(NewsNation) — Jade Dreith knew the dangers of fentanyl and was misled about a painkiller she bought, which ultimately led to her death, according to the woman’s sister.

Prosecutors say they now have the evidence to prove Dreith’s death was murder.

“This is murder without using a weapon,” Fresno County District Attorney Lisa Smittcamp said at a news conference. “This is murder without using a firearm. The weapon is fentanyl.”

Cassidy Gonzalez, 21, faces four felony counts including suspicion of murder. Another man, Alejandro Valverde-Nuno, is also facing charges as an accessory.

“(Jade) just got home from work and was given a pill she thought would help her back from hurting,” her sister Sage said. “She was folding laundry, eating a snack and fell asleep and never woke up.”

Fentanyl is a synthetic opioid with legitimate medical uses. It’s cheap and and powerful and increasingly common to find mixed with heroin or in pills.

On Wednesday, agents say they found 12,000 fentanyl pills hidden in boxes and bags of candy at Los Angeles International Airport.

The sheriff in Los Angeles County says the suspect tried walking through security with the bags and ran when caught.

In New York this month, police arrested a woman accused of hiding 15,000 fentanyl pills in a Lego box. The pills were imprinted with an M and the number 32 and resembled common painkillers.

At the time, it was New York City’s largest fentanyl bust, only to be outdone a week later when 300,000 pills and more than 20 pounds of powdered fentanyl were found.

The DEA says the fentanyl in communities across America is commonly made and smuggled from Mexico. Just this week, President Joe Biden and Mexico’s president said they’re reviewing joint efforts to combat fentanyl trafficking across the U.S.-Mexico border.

Wednesday, the Treasury Department sanctioned several individuals from the Sinaloa Cartel, which authorities believe is massively responsible for the trafficking of thousands of tons of drugs across the border.