New York police are stepping up collars of drug dealers, squeezing them for leads on the source of the “hot shots” (deadly doses). So far, there have been no arrests. While new to the Northeast, fentanyl has been linked to more than 100 deaths in California over the last 10 years. It may have come to the New York area as part of an attempt to widen the market with a more intense “designer” substitute for heroin. The surge comes amid signs of increased demand for the real thing. “We are arresting a larger percentage of people for heroin use,” says Anthony Voelker, chief of the New York police’s organized-crime bureau. Synthetic substitutes will only add to the cops’ woes. While publicity may temporarily scare away addicts, police are prepared for the worst. Says Voelker: “Something new may have entered the drug stream.”