DENVER -- A drug 3 1/2 times more powerful than heroin is being used and abused in Colorado.
Even more disturbing is that the drug has been legal for years in most states.
U-47700, a pharmaceutical research drug developed in the 1970s is a more potent alternative to morphine.
It was never tested on humans but is now being manufactured and sold by clandestine labs in Asia.
"They were never approved as pharmaceuticals. They never went through clinical trials. They were just developed. The actual compound was developed," said Michael Marlin, a medical toxicologist with University of Colorado Hospital.
"You're talking about something that the dosage is the equivalent of two grains of salt. That's what the dosage is," said Sgt. Jim Gerhardt with the Colorado Drug Investigators Association.
However, the drug is just starting to show up in the western United States. It's so new, the state has yet to make it illegal.
The FOX31 Problem Solvers have found only 10 states that have banned the drug, but the U.S. Drug Enforcement Agency is working to make it illegal nationwide.
However, manufacturers of synthetic opioids such as U-47700 are often one step ahead, able to alter the drug just enough to keep it legal.
"They make a more potent form. Every time they change it they make it more potent and dangerous so it's hard for the law to keep up with this," Gerhardt said.
Gerhardt said U-47700 is just one of many new synthetics that law enforcement is encountering.
"These synthetic opioids are so potent you essentially have to dilute it by mixing it in with heroin or something else because it's too powerful," he said.
Thirty-one states have reported overdose deaths from U-47700. That includes Colorado, where two people were killed in Boulder County in January.
But it was a case in Utah that thrust the drug into the national spotlight. Two 13-year-olds overdosed and died after buying the drug from a classmate who purchased it online.
"Basically, it works so people can't breathe or they don't breathe," Marlin said.
Hospitals are also very concerned, especially in Colorado, a state that already has a big drug problem.
"In Colorado, a person dies of a drug overdose every 10 hours. Since 2005, drug overdoses have actually been the leading cause of death, surpassing motor vehicle deaths," said Jamie Feld, an epidemiologist with the Boulder County Health Department.
Some synthetic opioids are so potent that first responders have been killed just touching them.
That's one reason the state is scrambling to equip law enforcement and other first responders with naloxone, a life-saving tool that can reverse the effects of an opioid overdose.
"Typically, people think about it in terms of the overdose of the user and that's an important function to be able to save a life, but we have to now start looking at it as if we may be saving our partner," Gerhardt said.
It's a new reality striking fear into drug investigators as synthetic opioids bring drug use from the shadows and into the light.