This is the final installment in a series that offers an inside look at the FBI on its 100th anniversary. FOX News was granted rare access for the reports, which examine the lives of bureau agents.

NEW YORK — For 22 years on the job at the FBI, Todd Letcher worked graveyard shifts, led national manhunts and did duty with SWAT teams in Atlanta.

One of 390 agents to retire this year, Letcher now is preparing to take on another dream job — at the new Yankee Stadium. FOX News shadowed Letcher on his last week at the FBI as he took a look back on his early years.

"It really was a calling ever since I was a child and saw 'The FBI Story' with Jimmy Stewart," he said. "It was something that I always wanted to do."

Click here to see more on Agent Letcher's service.

Even his first day with the FBI was full of unexpected turns.

"I thought it would be a regular orientation kind of day — I thought I'd be home at 5 o'clock. Turns out we developed some fugitives and it actually turned out that we didn't get home until three in the afternoon the next day," he said.

Currently the head of surveillance in New York City, Letcher has run with Atlanta SWAT and also headed up the manhunt for Eric Rudolph, the Olympic Park bomber.

"There was a lot of discussion about where he was, whether he was alive or dead or whether he was out of the country," Letcher said. "We always maintained he was alive, alone and living in North Carolina."

Officials caught up with Rudolph in North Carolina in 2003, and Letcher was there when Rudolph was sentencing to five consecutive life terms for murder.

"I remember that vividly — sitting in the court room, watching him at the defense table, the judge pronouncing the sentence: multiple life terms," he told FOX News. "I think there was a final realization in Rudolph's mind what was in front of him."

Now what's in front of Letcher is another chapter in his life as he moves into what he calls a "mind-boggling" position: head of security at the new Yankee Stadium under construction, a job that he says his work at the FBI has prepared him for.

"One of the primary things is the technical expertise I bring from the FBI," Letcher said. "You can really be very effective when you blend the surveillance technology with people."

Though the stadium won't be playing host to any Yankees games until next year, Fletcher is already out making his rounds. "I am a little early, but I got a good seat," he joked.

Letcher's sense of humor belies the gravity of his new job as head of security. The billion-dollar stadium will be a year-round venue with 52,000 seats — and will require a lot of careful tending.

"There will be cameras that are unmanned but controlled from a central point. There will be other types of technology that I won't get into specifically that can monitor access and egress," he said.

With the new Yankee stadium opening this spring, Letcher relishes his call up to the big show.

"I've had a dream job, absolutely, with the FBI," he said. "But how often do you in your career get a chance to do a second dream job?"

Click here for Part 1, a look at the next generation of agents in training at the FBI Academy in Quantico. Click here for Part 2, an exclusive look at a joint drug raid by FBI agents and Philadelphia police.