CHICAGO (CBS)– Officials charged 35 people after a federal and state investigation into a heroin and fentanyl drug-trafficking ring in Chicago’s West Garfield Park neighborhood revealed a drug delivery service accessed by a “heroin hotline.”

According to the U.S. Attorney’s Office, law enforcement agents from the Organized Crime Drug Enforcement Task Force and the Chicago High Intensity Drug Trafficking Task Force conducted a multi-year investigation called “Operation Road Rage.”

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The investigation yielded in the seizure of a kilogram of heroin–most of which contained fentanyl–approximately $100,000 in cash, five firearms and four vehicles, all recovered from the city’s West Side.

Officials said the offenders allegedly distributed the heroin and fentanyl through a driver delivery service. Customers who wanted to buy drugs would call a heroin hotline and operators identifying themselves as ‘Sean’ would answer the phone, according to the U.S. Attorney.

Then, the phone operators would dispatch drug distributors to various locations on the West Side to conduct the drug deals.

Undercover agents allegedly purchased narcotics from the drug ring on at least 50 occasions, according to the U.S. Attorney.

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The 35 individuals charged range in ages 21 to 56-years-old.

Twenty-two defendants were charged with federal drug offenses and 13 other defendants were charged in state complaints.

Two of the individuals are charged with drug conspiracy and are accused of being regular customers of the “Sean drug trafficking organization.”

Four of the defendants are accused of conspiring to distribute approximately 94.8 grams of fetanyl-laced heroin to an “undercover law enforcement officer” from August 2017 to March 2018.

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The charges carry maximum sentences of 20 years to life in prison.