It's a problem reaching epidemic proportions in the Tampa Bay area.
Fentanyl and fentanyl-laced pills were behind more than 500 deaths in Florida in 2014, and that number continues to rise year after year.
Some law enforcement officers call them the perfect "counterfeit pill," posing as common prescription drugs, like Xanax, but can kill a person with just one dose.
"The problem is fentanyl is between 50 and 100 times more powerful than just normal morphine and gets mixed into other powders that you don't know what you're taking," said Dr. Michael Sheehan, medical director or Operation PAR in Largo.
The resemblance is so convincing, sometimes officers won't know what they've seized until it is dropped off at a state crime lab.
ABC Action News got a rare look inside Florida Department of Law Enforcement's Tampa crime lab, where a team of technicians analyze what's inside the so-called "kill pills."
"Xanax, for instance, where it's been laced with fentanyl in it and maybe the person purchasing it was legitimately looking for xanax and didn't realize fentanyl was in it," said FDLE crime lab analyst Stephen Hanily.
Hanily says he alone has tracked three times the amount of fentanyl coming through his lab since last year.
According to the state Medical Examiner covering Pinellas and Pasco counties, there were 45 fentanyl-related deaths in 2015. They are on track to double that number with 40 fentanyl-related deaths reported between January and June of 2016.
"It's a very fatal pill to take," said Dr. Sheehan.
Law enforcement warns fentanyl found in fake prescription pills is produced on the black market, sometimes imported from foreign counties.
There are legitimate uses for fentanyl. It is typically regulated and prescribed by a doctor to terminally ill cancer patients in a time-release form.