A 24-year-old woman recently crossed the Mexican border in Nogales, Ariz., on foot, pushing an inconspicuous stroller. In addition to her two young children, it carried five pounds of fentanyl, a deadly opioid 50 times more powerful than heroin. Law enforcement intercepted the drug shipment this time. But many other packages get through, with fatal consequences.

As a recently retired 25-year public servant and former police chief of Nogales, I have seen firsthand the fentanyl crisis and the human carnage it wreaks. So it's with deep concern that I read about Sen. Bernie Sanders' bill to open the U.S. pharmaceutical market to foreign prescription medications.

The legislation, which would allow Americans to buy medicines directly from overseas suppliers, is intended to cut drug costs, since drugs from abroad are often cheaper than those in the United States. While well-intentioned, the legislation would vastly increase the flow of illegal narcotics and counterfeit drugs laced with fentanyl into the United States. Local law enforcement, already strained by narco traffickers, would find their time and their resources spread perilously thin.

Police nationwide are struggling to address an opioid crisis so severe that it's dramatically increased mortality rates for middle-aged, white Americans. Addicts face a double peril as Mexican cartels often lace prescription opioids with fentanyl.

"They think they're taking oxy, but they're actually taking fentanyl, and it's lights out," one Drug Enforcement Administration special agent recently said. In metro Phoenix alone, 32 people in the past two years died after taking counterfeit OxyContin pills laced with fentanyl that came from Mexico. Their average age was 35 — the youngest was just 16. And in 2014, the number of fentanyl-related deaths nationwide more than doubled in a single year to 4,200.

In the past few years, we've lost firefighters and college grads, senior citizens and avid outdoorsmen, to fentanyl that was brought across the border. I've seen the corpses and stood in front of the grieving families. Their preventable and untimely deaths have haunted me on the clock and off.

If the Sanders drug importation bill is passed, the dead may soon include patients who thought they were taking legitimate drugs for legal purposes. Right now, the United States has the safest prescription-drug supply chain on the planet, entirely because of the Food and Drug Administration's stringent restrictions on foreign-drug importation.

Most medicines are produced domestically. The ones that aren't made in America are imported via closely monitored supply chains to ensure that foreigners can't purposely or unwittingly ship fake drugs to Americans.

If we get rid of those protections and allow foreigners to ship medicines directly to Americans, bad actors will seize the chance to profit, even if it kills people. Narcos already know they can buy fentanyl for just a few thousand dollars and sell their counterfeit drugs for millions. Across the world, fake prescription drugs net criminals $200 billion, according to World Customs Organization estimates.

Proponents of the Sanders bill promise they can use foreign drug imports to cut costs without sacrificing quality. But the FDA is far less optimistic. The agency's top brass have warned Congress that they "cannot ensure the safety of drugs purchased from foreign sources."

Under the proposed bill, packages of medicines would come into the country largely unmonitored – and it is likely that many illicit drugs would slip in through the cracks. With the FDA unable to weed out fake and contaminated medicines from legitimate pills, responsibility will fall to local law enforcement.

Here in Arizona we're already on the front line of the battle against narcos — and that fight is pushing us to our limits. In December 2016, the Phoenix Law Enforcement Association described police officers' growing burden. "Staffing is decimated, overtime costs are skyrocketing, employees across the department are overworked and experiencing burnout," a spokesman described.

Departments across the country struggle with the same problems.

The proposed legislation would put law enforcement in a no-win situation. We don't have the resources or the manpower to take on more responsibility. Innocent patients will die from counterfeit medications after taking what they think are legitimate prescription pills.

The Sanders bill is intended to save lives and help patients afford medications. But every way I look at it, this legislation will cost lives.

Derek Arnson is the former Chief of Police in Nogales, Arizona.

If you would like to write an op-ed for the Washington Examiner, please read our guidelines on submissions.