Established in 1789 by George Washington, the US Marshals Service is the oldest law enforcement agency in the country.

As the enforcement arm of the US Federal Courts, the Marshals are tasked with capturing fugitives, serving federal arrest warrants, transporting prisoners, and overseeing the witness protection program.

The job puts agents directly in the way of the most dangerous criminals in the nation.

Photographer Brian Finke recently shadowed a US Marshal to get the inside view of what may be the most dangerous job in America.

Finke shared a number of the photos with us here, but the rest are collected in a new book out by PowerHouse books, “U.S. Marshals," available here.

Finke first became connected with the Marshals service because a friend from his high school, Cameron Welch, was a Deputy US Marshal. Welch works in the fugitive investigation division, which works with local and federal law enforcement to track down the most dangerous fugitives and assist in high-profile investigations.

After reconnecting, Welch offered Finke to come on a series of ride-alongs. On the first ride-along, Welch was tasked with assisting the Texas Rangers with capturing an escapee from a Texas prison. "We were driving 120 miles per hour on the freeway going to get this escaped convict. It was incredible to see," Finke told the Alexia Foundation.

Marshals don't care whether a fugitive is guilty or not and they don't solve crimes. Their only job is to find and apprehend the target. "This is really a big game, a mental and physical game," a US Marshal told the Washington Post."The bandit's job is to run; our job is to catch him."

Just because they aren't solving a crime, doesn't mean there isn't a lot of investigating. To track down fugitives, Marshals have to parse information given by relatives, search through databases for clues as to their whereabouts, and sit through days-long stakeouts. Then they have to apprehend the fugitive.

Raids can be extremely dangerous. Marshals often have to storm through doors without knowing what or who is on the other side. Fugitives are not always cooperative.

Marshals generally carry a Glock 40 as their primary handgun, but they also will carry AR-15 rifles in certain cases.

One time, Welch was tasked with investigating a man that had been threatening a federal judge. When Welch and his partner arrived, the man stormed out of his apartment with a pistol pointed at Welch. He says it was one of the closest calls of his career.

It can be an emotionally draining profession. Welch says he's been in situations where fugitives commit suicide when they arrive to avoid going back to prison.

Brian Finke/PowerHouse Books

The Marshals are not without a sense of humor. Welch frequently plays music when preparing for raids. Once, after apprehending a fugitive, his car began playing Jay-Z's "On To The Next One," as he placed the handcuffed man in the car. People in the neighborhood were startled.

Brian Finke/PowerHouse Books

Despite the dangers, Welch says that the profession is "addictive." As soon as he closes one case, he's excited to get started on the next one. "It's dangerous, but its rewarding to know that I'm making a difference in other people's lives..." Welch told Edith Zimmerman in the foreword to the book.

Brian Finke/PowerHouse Books

"For me it was amazing, putting on bullet proof vests and riding in right behind them. I had total respect for what they do," Finke said of the project in an interview with the Alexia Foundation. "It was just such an amazing experience – being there with them and being in awe of what they do."