Fentanyl is a highly potent synthetic piperidine opioid primarily used as an analgesic. It is 30 to 50 times more potent than heroin and 50 to 100 times more potent than morphine. From Wikipedia
The gripping story of Luke D'Wit's calculated murders of Carol and Stephen Baxter is detailed in a new ITV series highlighting one of Essex Police's most complex investigations.