In Los Angeles County Sheriff Jim McDonnell, we find a man determined to restore a high gloss to the badge and the image of policing in America.

The Los Angeles County Sheriff's Department employs more than 18,000 people and operates on a budget of $3.4 billion.

The LASD covers more than 4,000 square miles in a county of 10 million people, and offers policing services for 42 cities and 130 unincorporated areas. The department protects 42 courthouses, seven jails, six major hospitals, and train and bus lines.

As a young man, the Boston-bred son of Irish immigrants trekked 3,000 miles across the country to attend the Los Angeles Police Academy.

McDonnell spent 28 years with the LAPD, quickly climbing the ranks, stopping just short of nabbing the title of chief. His then-boss, now New York Police Commissioner, William Bratton, adopted McDonnell's plan for community policing, which would help reform the LAPD.

McDonnell would ultimately get the coveted chief's job at the Long Beach Police Department before winning the election for L.A. County Sheriff in 2014.

He's a hero in the truest sense: McDonnell was once awarded the coveted Public Safety Officer Medal of Valor for pulling three people out of a burning building.

But it's no secret McDonnell inherited a scandalous mess: brutal jail beatings by deputies, cover-ups by the top brass.

As a result, McDonnell's predecessor, Lee Baca, is facing prison time, and Baca's Undersheriff Paul Tanaka has also been criminally charged.

"Things were tolerated that shouldn't have been tolerated," said McDonnell. "Most of the department was disgusted by it."

McDonnell's policy is zero tolerance. It starts with who deserves to wear the badge. McDonnell is raising the bar, and it starts at recruitment.

"Right now for every 100 applicants we have, four make it to the academy," said McDonnell.

Many of L.A.'s problems with policing are the nation's problems.

McDonnell wants transparency, and he thinks body-cams may be one solution. But for a department the size of the LASD, the cost is prohibitive, and the technology is not foolproof in terms of facts.

When it comes to use-of-force issues and high-profile flashpoints like Ferguson, Missouri and Baltimore, McDonnell isn't afraid to scold the news media for fanning flames of hostility.

McDonnell, like anyone in charge of a police agency, has to worry not just about protecting the public, but protecting the rank and file increasingly under siege.

Terrorism is now a part of every department's concern. The San Bernardino terrorist attack was just 90 miles away from Los Angeles.

In San Bernardino, a neighbor of the terrorists reportedly saw suspicious behavior but was afraid to call police. McDonnell says the public has got to get brave.

"The public is everywhere, to be able to see when something doesn't look right and to be able to have the courage to act on that, and for us to be approachable enough that when somebody calls and says 'I can't say why this doesn't feel right but could you take a look?' We're happy to come and take a look. Their call could help and save a bunch of lives."

McDonnell does believe public safety is everyone's concern, not just police agencies.

"When you look at people in our state prison system, many -- probably 90 percent -- are either illiterate or functionally illiterate," said McDonnell. "You wonder had they been given the basics on how to read and write at an early age, would they have taken the path they did? I argue probably not in many cases."