A Portland police officer and dog search Forest Street in Portland in this May 2015 file photo. Credit: Troy R. Bennett / BDN

Drug-sniffing dogs are a powerful weapon in law enforcement’s battle against illegal narcotics. If a police officer pulls over someone’s vehicle, and a dog’s powerful nose picks up the scent of illicit substances such as heroin, methamphetamine, crack or cocaine, the officer can legally search the car without a warrant.

But the dominance of a newer, deadlier drug in Maine has introduced a challenge for law enforcement tools that primarily rely on their noses. Fentanyl, the highly potent synthetic opioid that’s fueling the state’s overdose death toll, has increasingly supplanted the street market for heroin, police say. And for safety concerns and legal reasons, drug dogs are not trained to detect it.

“My sense is, yeah, it’s a huge issue,” said Kyle Heyen, a South Dakota-based working dog expert and former police dog handler. “It’s getting through. It’s all over.”

While it’s difficult, if not impossible, to estimate the degree to which the drug is slipping by police, experts said, the issue spotlights yet another way fentanyl has been an especially devious force in a worsening public health crisis that will take more than just law enforcement to fix. The drug drove record fatal overdoses in Maine last year, causing 77 percent of the 636 drug deaths in 2021, state data show. Fentanyl can be up to 100 times more potent than heroin.

Meanwhile, instances where dogs have alerted to fentanyl are renewing long-running concerns about dogs’ reliability in the field.

Dog trainers, former handlers and police officials said fentanyl’s potency is one reason police don’t allow their dogs to interact with it in training over fears they could inhale it. Medical officials have pushed back against what they see as an exaggerated panic over accidentally overdosing from fentanyl after coming into incidental contact with it. The American College of Medical Toxicology and American Academy of Clinical Toxicology said first responders should be careful around the drug, including by using masks and knowing how to respond to the signs of an overdose, but the group has not seen any evidence of overdose based on touching fentanyl or breathing the air around it. 

Still, law enforcement officials said they worry about increasing the number of occasions they expose their dogs in training sessions that involve imprinting on how something smells.

“Could a dog be trained to find it? Yes. Could it be done safely? No. That’s my opinion,” Heyen said. “I wouldn’t train it because that means I’ve got to handle it. One ‘oops’ is all it takes.”

There is another complication. Warrantless searches are only allowed if dogs alert to illegal substances, and, unlike heroin, fentanyl can be prescribed to treat severe pain. As a result, training dogs to detect fentanyl could lead to searches of people who haven’t done anything illegal, in violation of their Fourth Amendment rights.

For that reason, “We do not train a dog to alert to fentanyl, as that alert could jeopardize admission of any evidence seized,” said David Procopio, director of media communications for the Massachusetts State Police.

Officials with the Maine State Police and Maine Criminal Justice Academy, the agencies that train and certify dog teams, declined to discuss in interviews how they’ve adapted their methods to the prevalence of fentanyl. However, the state’s chief dog trainer testified in court as recently as December that narcotics dogs are not trained to find fentanyl.

The rise of fentanyl has created new opportunities to scrutinize dogs and their oversight.

For example, research has shown handlers can cue the dogs to alert, often by accident. But courts have made it hard to challenge a dog sniff when the animal has been certified, even if the dog makes mistakes or deviates from its training in the field. Lawyers have also complained about the difficulty of getting field records that describe a dog’s behavior outside of training scenarios.

Now, defense attorneys have run into situations where police find fentanyl on their client even when the dog wasn’t trained on the drug.

“The trend for the last decade has been fentanyl, not heroin. It’s been fentanyl. In fact, I haven’t seen a case that involved heroin in years,” Heather Gonzales, a lawyer with the Federal Defenders Office, argued during an evidence suppression hearing last December in U.S. District Court in Portland.

A state police trooper stopped her client, Jenny Santana-Vasquez, for speeding in late 2018. He summoned a drug dog, a yellow lab named Mack, to the scene when he suspected deeper criminal activity was afoot.

When police found fentanyl on her client, Gonzales argued Mack’s alert on the exterior of Santana-Vasquez’s Jeep should be considered unreliable and was one of several reasons to suspect Mack’s credibility.

“The K9s in Maine aren’t trained in fentanyl, but they’re hitting on vehicles, again and again and again, when the only drug that’s found is fentanyl, like in this case,” Gonzales argued, according to a transcript of the hearing.

Mack’s handler, Cpl. Jesse Duda, testified that Mack likely picked up on residual odors of drugs he is trained to detect, a theory that experts said would go against how dogs are usually trained. When dogs are learning to alert in the presence of drugs, they are also learning not to alert where a trainer previously hid drugs, said Andy Falco, a dog training expert and former police dog handler.

Judge George Z. Singal ultimately sided with prosecutors and allowed the case to move forward.

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Callie Ferguson

Callie Ferguson is an investigative reporter for the Bangor Daily News. She writes about criminal justice, police and housing.