A deluge of powerful, pure crystal methamphetamine is “storming back into Southeastern Pennsylvania,” buoyed by savvy drug dealers looking to expand beyond opioids, investigators in Chester County said Wednesday.

District Attorney Thomas P. Hogan said aggressive Mexican cartels have been “flooding the market” with the drug at least since last year, when his office first noticed the trend.

“They’re responding to supply and demand, like any other business. When they see opioid use going down, they’re responding with this," Hogan said. “Like Big Pharma, they’re getting people to use the drugs and get hooked, and then they’re taking advantage of supply lines that have already been established.”

Hogan described the trend hours after a midlevel meth dealer was arrested in the county.

Ruben Vargas-Santillan, a Mexican national living in Reading illegally, has been charged with multiple felony drug offenses after a months-long investigation by Hogan’s office. Vargas-Santillan, 35, allegedly sold cocaine and then crystal meth to an informant, each time steadily increasing the amount of meth being sold.

When investigators arrested him and raided his home in Berks County, they found nearly a pound of crystal meth as well as several pounds of cocaine and marijuana, according to the affidavit of probable cause for his arrest.

“This is a medium-sized case,” Hogan said. “But it demonstrates a pattern we’re seeing in Chester County and throughout the country.”

Laura Hendrick, the field intelligence manager for the Philadelphia office of the Drug Enforcement Administration, said crystal meth seizures have spiked nationally in the last five years, jumping 50 percent in Pennsylvania since 2015.

Locally, the drug’s popularity initially waned after the mid-2000s, according to Hogan, who noted that many of the arrests back then were for “biker meth,” a less potent homemade variety. This more recent wave of sales features a version of the drug that is “good, clear, and clean,” made in labs in the Mexican desert and smuggled over the country’s southwestern border.

The supply is meeting a demand, mostly opioid users who either take the drug to help mitigate withdrawal symptoms between fixes, or in combination with heroin or fentanyl to prevent fatal overdoses.

Regardless, Hendrick said, the users are finding a ready supply.

“The business model for cartels is all profit driven — meth is easy to make and produce,” she said. “If they can put a lab together, they already have markets where they push heroin and fentanyl, and they supply these new drugs on top of those as they look for users.”

In the last year, law enforcement officials in Chester County have handled high-profile cases in which meth played a role. Nicholas Spadaro, a Valley Township resident, killed another man in the middle of a meth deal in November, Hogan said. A month later, Daniel Proffitt allegedly strangled his girlfriend while high on the stimulant.

And last May, Brian Touchton, 42, fled from state police who tried to pull him over while he was drunk and high on meth, sparking a police-involved shooting, according to Hogan.

“We’re sounding the alarm now because law enforcement is dealing with it, and we want the public to be aware that we’re dealing with it,” Hogan said. "Because crystal meth is back, and it’s back with a vengeance.”