A voluntary one-day survey of 643 Hennepin County jail inmates shows how the criminal justice system hurts the working poor, said Hennepin County Sheriff Rich Stanek.

The One-Day Snapshot Study was conducted on August 25, 2018. Among those inmates who responded a majority indicated they earned less than $20,000 per year, Stanek said.

"Eighty-eight percent of those can't afford to pay their court-ordered bail. And 71 percent of those are in jail for a non-violent charge," he said. "And so we've always said, look we should lock up those we are afraid of not those that can't afford to pay."

The results of the study were analyzed by Ronal Serpas, a criminology professor at Loyola University in New Orleans, La., and a former superintendent for the New Orleans Police Department.

Serpas said the data is an important contribution to the nationwide discussion about problems plaguing the nation's criminal justice system.

"More and more cities, counties are recognizing that, as is the case here, significant percentages of those held in jails are not a threat to the public, and are being housed at an incredible cost," said Serpas in a press release. "This study demonstrates this well and will be a valuable launching pad for a lot of critical thinking needed on this topic."

In the past, Stanek has conducted surveys on the prevalence of mental illness and opioid addiction in the inmate population. Both studies revealed that inmates are particularly hit hard by both crises.

Stanek leaves office on Monday.

"Jails should never be the warehouses for the mental-ill or the chemically dependent in society or as substitute shelters for the homeless," said Stanek. "It is unacceptable."

After 12 years in office, Stanek is leaving after losing his re-election bid to Dave Hutchinson. Stanek said he didn't know specifically what he'll do next, but believes he will stay involved in the causes he's passionate about.

"I want to continue to work on things that affect public safety," said Stanek. "It's what I dedicated 35 years of my adult life to and I will continue to moving into the future."