CLEARWATER — Counterfeit Xanax pills laced with Fentanyl likely have killed nine people in Pinellas County this year, Sheriff Bob Gualtieri said Monday."People need to immediately stop buying Xanax on the street because their life literally depends on it," he said at a news conference.The agency has confirmed three deaths and suspects six more linked to the pills. Nine others sold the pills to undercover law enforcement officers, Gualtieri said. "Nine people are dead. Nine more would have been," he said. The outbreak seems to be contained to Pinellas, Gualtieri said. But much remains unclear, including the pills' source, manufacturer and composition.Xanax, used to treat anxiety, is cheap on the streets at $3 to $5 a pill. Gualtieri said supply and demand seems to have been consistent over the past few years.Fentanyl, a synthetic opioid 80 times more potent than morphine and 50 times more potent than heroin, has legitimate medical uses, such as pain relief in cancer patients. Because of its rapid onset, it's usually taken in a time-release patch — not orally, which doesn't control for its rapid onset.Combining the two has proved to be lethal."It's so strong, it's killing them," Gualtieri said.The counterfeit pills are made to look like Xanax, but are thinner and have a stamped-on number.The Sheriff's Office is seeing a sharp uptick in Fentanyl mixed with other drugs, including heroin, in the past two years.In 2014, the Sheriff's Office lab saw 14 such cases. In 2015, it saw 71.And this year, it's on track for more than 100.Most recently, Gualtieri said, a 25-year-old woman died after taking drugs mixed with Fentanyl in Dunedin. Hers was the first overdose-related death north of Largo.And three others overdosed on a new opioid on the street, called U-47700, between October 2015 and January 2016, the sheriff said.Gualtieri said he knows his office can't stop drug abuse. But he wants buyers to be aware."It may well kill them," he said. "There's no other way to put it."Contact Claire McNeill at [email protected] or (727) 893-8321.