Dozens of people are facing criminal charges after a sweeping 14-month federal and state investigation into the trafficking of heroin, cocaine and fentanyl — a drug that led to a huge spike in deaths last year.

A task force also took more than a dozen guns, $380,000 in cash and 3 kilograms each of heroin and cocaine off the street as part of “Operation Sweet Dreams.” Authorities wiretapped cellphones, bought drugs undercover and conducted extensive surveillance during an investigation aimed at drug dealers in Garfield Park, Homan Square and North Lawndale, including members of the Unknown Vice Lords gang.

U.S. Attorney Zachary Fardon said 148 grams of the seized heroin was laced with fentanyl. A rash of overdoses in 2015 caused by such drugs — including more than 100 in a three-day period — sparked the task force’s investigation, according to Dennis Wichern, the special agent in charge of the Chicago Field Division of the Drug Enforcement Administration.

“From that, spawned this case,” Wichern said during a press conference at the Dirksen Federal Courthouse.

Fardon said the sweep is a sign of his office’s “ongoing commitment to use all of the tools we have in the federal shed” to combat the violence in Chicago fueled by guns and drugs. That violence has drawn routine commentary from President Donald Trump.

“Obviously, Chicago’s received a lot of attention already from this president and this administration — and rightfully so,” Fardon said. “I think our problems deserve that kind of attention.”

A Cook County Medical Examiner’s spokeswoman said the office saw 527 fentanyl-related deaths in 2016, compared with 103 in 2015. However, the 2016 number is not final because some toxicology tests may still be pending.

One defendant in the case bought 2 kilograms of heroin for $132,800 in cash in the Bucktown neighborhood last October, the feds say. Another agreed to sell his Chevrolet conversion van in exchange for a kilogram of cocaine.

Fardon said 69 people face charges after the sweep, including 18 people who face charges in federal court and 51 who face charges in state court. However, a spokeswoman for Cook County State’s Attorney Kim Foxx said only 33 people face charges in state court as a result of the operation.

Authorities began making arrests Thursday morning, but at least one federal defendant was still at large Thursday afternoon.