More than two dozen convicted felons and reputed gang members have been arrested in connection with the sale of some dangerous batches of heroin laced with the powerful painkiller fentanyl, which might lead to a rise in drug overdose deaths in the Chicago area.

The roundups, that began earlier in the day, came after the Chicago Police Department's narcotics unit underwent an investigation into the sale of fentanyl-laced heroin, that included the use of undercover officers buying the drugs on the streets to build cases against more than 25 people. All of them have been facing state and federal charges. Police and federal agents continued to round up additional suspects on Thursday night.

Dozens of people have died of fentanyl-related overdoses over the past years. Last fall, the Tribune first reported perhaps the Chicago area's most significant outbreak of fentanyl-related overdoses in about a decade, when 74 people overdosed on the potent painkiller within a 72-hour period ended on October 1.

Chicago police at the time thought that those victims purchased the painkillers primarily at one of several drug spots on the West Side, where fentanyl have often been mixed with heroin.Drug dealers have cut heroin with fentanyl to make a more potent product. The powerful, euphoria-inducing narcotic is 30 to 50 times more potent than heroin and significantly increases the risk of overdose deaths.

Dealers, however, continued to consciously market the dangerous mix, and users continue to seek it out. As they have for years, dealers typically set up shop on the West Side along the Eisenhower Expressway, which has garnered the nickname "Heroin Highway" because of drug users making the trek from the suburbs to get their fix.

By Prakriti Neogi