MINNEAPOLIS — The Hennepin County medical examiner has attributed five additional overdose deaths to the powerful opioid carfentanil.

The opioid is relatively new to Minnesota and is 10,000 times more potent than morphine and 100 stronger than fentanyl. The drug is used as a tranquilizer for elephants or other large animals.

Because routine drug and alcohol screenings don’t detect the drug, samples have to be sent to a specialized lab. Hennepin County Medical Examiner Dr. Andrew Baker says his office continues to order the special tests on a case-by-case basis after considering the autopsy findings, investigative and lab results.