A two-year operation utilizing more than 500 federal agents and police officers culminated recently with the arrest of nearly 100-suspects.

DENVER (Reuters) - At least 80 people have been arrested in what federal, state and local law enforcement officials on Thursday called the largest drug bust in Colorado history, a sweep that grew out of an investigation of violent bank robberies.

U.S. Attorney John Walsh said 58 pounds of cocaine, 2.2 pounds of crack cocaine and one pound of methamphetamine were seized in the two-year operation undertaken by 500 federal agents and police officers.

"Today our streets are safer, and the drug trade in Colorado has suffered a massive blow," Walsh said in a statement.

In addition to the illegal drugs, agents also seized 12 weapons, including assault rifles and handguns, and more than $400,000 in cash.

The drug trafficking probe began in December 2009 and evolved from FBI investigations of a series of 16 takeover bank robberies in the Denver area.

"What triggered this investigation was the very violent activity of some hard-core gang members," said Aurora, Colorado, Police Chief Daniel Oates. "Once we focused on them, our investigation led to a complex narcotics conspiracy."

Twenty-five suspected gang members have been charged with the bank robberies, according to prosecutors.

A total of 97 people have been charged in either federal or state court related to the drug sweep, and all but 17 had been taken into custody, authorities said. They said the sweep marked the biggest mass arrest for drug trafficking ever in the state.

If convicted, most of the defendants charged in federal court face sentences ranging from 10 years in prison to life terms and up to $10 million in fines, prosecutors said.

Defendants charged in state court could receive mandatory minimum prison sentences depending on the charges, they said.

Points to consider:

The largest drug bust in Colorado history climaxed with a total of 97-individuals charged in either federal or state court. The arrests initially began with investigators targeting the very violent activity of some hard-core gang members, but ended with a mass arrest for drug trafficking. At the time of the bust agents seized 12-weapons, including assault rifles and handguns, more than $400,000 in cash, 58 pounds of cocaine, 2.2 pounds of crack cocaine and one pound of methamphetamine. Consider that in the Federal Bureau of Investigation’s (FBI) National Gang Intelligence Center (NGIC) 2011 assessment and trends report, the FBI found that gangs are expanding, evolving and posing an increasing threat to US communities nationwide. According to the report, many gangs had in fact become sophisticated criminal networks that had developed close working relationships with members and associates of transnational criminal/drug trafficking organizations in an effort to distribute wholesale quantities of drugs.