CENTENNIAL, Colo. (KDVR) — A lengthy wiretap investigation helped law enforcement bust a drug operation, leading to what’s being called one of the largest fentanyl pill seizures in Colorado history.

According to 18th Judicial District Attorney John Kellner, about 200,000 fentanyl pills were recovered during the investigation along with 9.4 lbs of heroin, 1 kilogram of cocaine, four guns and $60,000 in merchandise that is believed to have been stolen.

Kellner said this started with a single purchase in December of 2021 and then grew into the wiretap investigation and eventually led to eight arrests.

“It starts with a small case and then it can be built into something meaningful,” he said.

The investigation included several different seizures, the biggest of which was 170,000 pills that were taken outside of an apartment complex in Aurora.

Kellner said those pills can be sold on the street for about $10 each.

Through the investigation, Kellner said there remains one unidentified person who is believed to be the primary source for bringing the drugs across the border and into the Denver area. This person is believed to be in contact with drug organizations in Mexico.

“We’re making the best dent we can possible in the flow of drugs coming up into this state,” Drug Enforcement Administration Special Agent in Charge Brian Besser said.

Besser said that the geography and highway infrastructure in Denver make it a vital location for cartel drug distribution.

“The I-70 and I-25 corridors are where deadly drugs head north and east, and money heads south,” he said.

A recent report from the District of Colorado U.S. Attorney’s Office said law enforcement has seized 2,084,633 dosage units of fentanyl through the first five months of 2022. This is more than 400,000 more units seized than all of 2021. The announcement Wednesday will surely continue to push Colorado law enforcement’s record-setting seizure year for the synthetic opioid.

You can watch a replay of the announcement in the FOX31 NOW player above.