Denver Police are seeing an increase of the drug fentanyl . Police confiscated bricks of the drug believed to be manufactured by drug cartels in Mexico. The drug has plagued many U.S Cities and up until now has always been found in smaller quantities in Denver. Police are concerned because fentanyl is very potent. More than 2-milligrams of the drug can kill someone. Illegal fentanyl made by the cartels is made to make money and without regard to safety.The Denver Department of Public Health and Environment is concerned about illegal fentanyl because it's not only dangerous, but also cheap and easy for addicts to get.