The FBI has transferred coordination of a task force for the investigation into the "Chicago Tylenol Murders" to local police, the Arlington Heights Police Department announced Friday in a news release.
In 1982, seven people died after taking cyanide-laced Tylenol, which was consumed over three days in Chicago and its suburbs.
No one was ever charged for the killings.
Victims of the poisoned Tylenol included Stanley Janus, 25, and Theresa Janus, 19, both of Lisle; Mary McFarland, 31, of Elmhurst; and Mary Reiner, 27, of Winfield, among others. All seven victims were found to have ingested the cyanide-laced Extra Strength Tylenol capsules on or shortly after Sept. 29, 1982.
The deaths led Johnson & Johnson to recall some 31 million bottles of Tylenol and led to the introduction of tamper-resistant packaging.
The FBI-led task force was established in 2007, along with the Illinois State Police and police departments in Arlington Heights, Elk Grove Village, Lombard, Schaumburg, Chicago and Winfield.
The FBI will continue to provide resources as needed to assist the investigation, according to the release.