An increasing number of fake prescription pills that contain potentially deadly fentanyl are helping drive overdose death rates to record levels in the U.S., including some now manufactured in rainbow colors designed to look like candy, federal officials said Tuesday. Drug Enforcement Administration agents are working to crack down on violent drug cartels in Mexico believed to be trafficking the drugs into the U.S., Attorney General Merrick Garland said. Between May and September, the DEA and local police around the country seized more than 10 million fentanyl pills and hundreds of pounds of powder, he said.