The following is a script of "The Gaskos" which aired on Nov. 24, 2013, and was rebroadcast on Sept. 14, 2014. Steve Kroft is the correspondent. Tanya Simon, producer.

Charlie and Carol Gasko were an elderly couple who moved to Santa Monica, Calif., sometime in early 1997 to begin a new phase of their life. For the next 14 years, they did almost nothing that was memorable. And as we first reported in November, they would be of absolutely no interest, if it weren't for the fact that Charlie Gasko turned out to be James "Whitey" Bulger, the notorious Boston gangster, and longtime fugitive who is now in prison serving two lifetime sentences. Carol Gasko was actually Catherine Greig, Whitey's long time girlfriend and caregiver.

The story of how they managed to elude an international manhunt for so long while hiding in plain sight is interesting. And tonight you'll hear it from the Gasko's neighbors and for the first time from the federal agents who finally unraveled the case, with the help of a boob job and an alley cat.

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Whitey Bulger befriended a man to gain an ali...

If you were forced into retirement, with a comfortable nest egg, and a desire to be left completely alone there is no place better place than Santa Monica, Calif. This low key, seaside suburb of L.A. is shared by transients and tourists, hippies and hedonists, celebrities and lots of senior citizens attracted to the climate and an abundance of inexpensive rent-controlled apartments, just a few blocks from the ocean. Places like the Princess Eugenia on Third St., which is where Charlie and Carol Gasko, a childless couple from Chicago, lived for 14 years without attracting much attention from long time neighbors or landlords. Josh Bond is the building manager.

Steve Kroft: What were they like?

Josh Bond: They were-- like, the nice retired old couple that lived in the apartment next to me.

Steve Kroft: Good tenants?

Josh Bond: Excellent tenants. Never complained. Always paid rent on time.

Steve Kroft: In cash.

Josh Bond: In cash.

Janus Goodwin lived down the hall.

Janus Goodwin: They had nothing. And they never went out. They never had food delivered. She never dressed nicely.

"They were-- like, the nice retired old couple that lived in the apartment next to me."

Steve Kroft: You thought they were poor?

Janus Goodwin: Yes, without a doubt.

The one thing everyone remembers about the Gaskos is that they loved animals and always made a fuss over the ones in the neighborhood. Barbara Gluck remembers that Carol Gasko always fed a stray cat, after its owner had died.

Barbara Gluck tells Steve Kroft about learnin...

Barbara Gluck: She would pet it, you know, and be sweet to it and she put a plate of food like out here.

Steve Kroft: And what about Charlie Gasko?

Barbara Gluck: You know, he always had a hat on and dark glasses. I have to say it was mysterious to me why such a lovely woman like that was hanging out with that guy, that old grumpy man. I could never figure that one out. Until I heard they had 800,000 something dollars in the wall. And then I went, "Oh, OK" you know?

Money wasn't the only thing found in the Gaskos' apartment on June 22, 2011, when the FBI stopped by and ended what it called the most extensive manhunt in the bureau's history.

Scott Garriola: Weapons-- weapons all over the apartment. I mean, weapons by his nightstand, weapons under the windowsill. Shotguns, Mini-Rugers, rifles.

Steve Kroft: Loaded?

Scott Garriola: Loaded, ready to go.

What had started out as a routine day for Special Agent Scott Garriola -- who was in charge of hunting fugitives in LA -- would turn into one of the most interesting days of his career. After getting a call to stake out a building in Santa Monica, he notified his backup team with the LAPD.

Scott Garriola: I had four guys working that day and we got a tip on Whitey Bulger and "I'll see you there in about an hour." And invariably the--texts return, "Who's Whitey Bulger," so.

Steve Kroft: Really?

Scott Garriola: Yeah, a few of 'em. So I had to remind 'em-- gently remind 'em who Whitey Bulger was.

Steve Kroft: That he was No. 1 of the F.B.I.'s Most Wanted List--

Scott Garriola: No.1, yeah. Big ea-- big East Coast figure but-- so on the West Coast not so much.

The cops in LA were focused on gang bangers and cartel members, not some retired Irish mobster, who hadn't been spotted in 16 years, but then few mobsters have ever been as infamous in a city as Whitey Bulger was in Boston, and his reputation was for more than just being grumpy.

Besides extortion and flooding the city with cocaine, Bulger routinely performed or ordered executions, some at close range, some with a hail of bullets, and at least one by strangulation after which it's been said he took a nap. Special Agent Rich Teahan who ran the FBI's Whitey Bulger fugitive task force had heard it all.

Rich Teahan: Bulger was charged with 19 counts of murder. He was charged with other crimes. He was a scorch to the society in South Boston, his own community.

He was also a scourge to the FBI, and a great source of embarrassment to Teahan, Special Agent Phil Torsney and others on the task force. Years earlier, Whitey Bulger had infiltrated the Boston office of the FBI and bought off agents who protected him and plied him with information including the tip that allowed Bulger to flee just days before he was to be indicted.

Phil Torsney: We really had to catch this guy to establish credibility after all the other issues. And it was just a matter of bringing this guy back to Boston.

When Torsney -- now retired -- and Agent Tommy MacDonald joined the Bulger task force in 2009, the joke was Bulger was on the FBI's least wanted list. There hadn't been a credible lead in more than a decade. And their efforts in Bulger's old neighborhood of South Boston were met with mistrust and ridicule.

Phil Torsney: Some people, they told us right out front, "You guys aren't looking for that guy." People just made the assumption we had him stashed somewhere. I mean, people really thought that kinda thing.

Tommy MacDonald: Despite that mindset that "we're not gonna help you" the FBI still got it done.

Steve Kroft: Took 16 years.

Tommy MacDonald: Took 16 years. Yeah, this was not a typical fugitive.

The FBI says Bulger had planned his getaway years in advance, with money set aside and a fake identity for a Thomas Baxter. During his first two years on the lam, Bulger was in touch with friends and family shuttling between New York, Chicago and the resort town of Grand Isle, La., where he rented a house until his identity was compromised. After that it seemed as if Bulger had disappeared from the face of the Earth except for alleged sightings from all over the world.

Steve Kroft: How many of these tips do you think mighta been true?

Phil Torsney: Boy there was thousands and thousands of tips. And I think -- I don't think that any of 'em were true.

One of the obstacles were there were really no good photographs of Bulger or his longtime live-in girlfriend Catherine Greig, a former dental hygienist. The FBI often noted the couple shared a love of animals, especially dogs and cats, and asked veterinarians to be on the lookout. There were reports that Greig once had breast implants and other plastic surgery in Boston, so the task force reached out to physicians. Eventually they got a call from a Dr. Matthias Donelan, who had located her files in storage.

Tommy MacDonald: I was trying to leave the office a little early to catch one of my kids' ballgames. And I said, "Well, listen-- I'm gonna swing by in the morning and pick those up." And they said to me-- "Do you want the photos too?" And I said, "You have photos?" And they said, "Yeah, we have photos." I said, "We'll be there in 15 minutes."

The breast implant lead produced a treasure trove of high resolution Catherine Greig photographs that would help crack the case. The FBI decided to switch strategies, going after the girlfriend in order to catch the gangster.

[PSA: This is an announcement by the FBI...]

The FBI on created this public service announcement.

[PSA: 60-year-old Greig is the girlfriend of 81-year-old Bulger...]

It ran it in 14 markets on daytime talk shows--aimed at women.

[PSA: Call the tip line at 1-800-Call-FBI.]

And it didn't take long. The very next morning the Bulger task force got three messages from someone that used to live in Santa Monica and was 100 percent certain that Charlie and Carol Gasko, apartment 303 at the Princess Eugenia apartments were the people they were looking for. The descriptions and the age difference matched and Deputy U.S. Marshall Neil Sullivan who handled the lead said there was another piece of tantalizing information.

Neil Sullivan: The tipster specifically described that they were caring for this cat and their love for this cat. So that was just one piece of the puzzle on the tip that added up to saying "if this isn't them it's something we better check out immediately because it sure sounds like them."

A search of the FBI's computer database for the Gaskos raised another red flag, not for what it found, but for what it didn't.

Neil Sullivan: Basically like they were ghosts.

Steve Kroft: No driver's license--

Neil Sullivan: Exactly. No driver's license, no California ID, like they didn't exist.

Steve Kroft: That's the apartment.

Scott Garriola: Right, that corner on the third floor.

Steve Kroft: On the right-hand side?

Scott Garriola: Yup

By early afternoon FBI Agent Scott Gariolla had set up a number of surveillance posts, and had already met with apartment manager Josh Bond to talk about his tenants.

Josh Bond: He closed the door, threw down a folder and opened it up and said, "Are these the people that live in Apartment 303?"

Steve Kroft: Did you say anything when you saw the pictures?

Josh Bond: Yeah. I mean, my (LAUGH) initial reaction was, "Holy shit."

Steve Kroft: You're livin' next door to a gangster.

Josh Bond: Well I still didn't really know who he was

But it didn't take him long to figure it out. While the FBI was mulling its options, Bond logged on to Bulger's Wikipedia page.

Josh Bond: And I'm kinda scrolling down. It's like, "Oh wow, this guy's serious." It's, like, murders and extortion. And then I get to the bottom and there's this-- this thing. It's like--from one of his old, you know, people saying, "Well, the last time I saw him, he said, you know, when he goes out he's gonna have guns and he's gonna be ready to take people with him." I was like, "Oooh, maybe I shouldn't be involved in this."

Steve Kroft: I mean, we were sitting here laughing about it but he is a pretty serious guy.

Josh Bond: Yeah, yeah.

Steve Kroft: And he killed a lotta people--or had them killed.

Josh Bond: I didn't know that at the time.

Bond told the FBI he wasn't going to knock on the Gasko's door because there was a note posted expressly asking people not to bother them. Carol had told the neighbors that Charlie was showing signs of dementia.

Scott Garriola: We were back there...

So Garriola devised a ruse involving the Gaskos' storage locker in the garage.

Scott Garriola: It had the name Gasko across it and Apartment 303.

He had the manager call and tell them their locker had been broken into and that he needed someone to come down to see if anything was missing, Carol Gasko said her husband would be right down.

Scott Garriola: We just rushed him.

Steve Kroft: You mean, guns out? "FBI--

Scott Garriola: Sure.

Steve Kroft: --don't move."

Scott Garriola: --gave the words, "Hey, FBI, you know, get your hands up." He turned around and hands went up right away. And then at that moment we told him get down on his knees and he gave us-- (laugh) yeah, he gave us a, "I ain't gettin' down on my f'ing knees."

When "Whitey" Bulger finally got pinched

Steve Kroft: Didn't wanna get his pants dirty.

Scott Garriola: Didn't wanna get his pants dirty. You know, wearing white and seeing the oil on the ground I guess he didn't want get down in oil.

Even at 81, this was a man used to being in control.

Scott Garriola: I asked him to identify himself and that didn't go over well. He asked me to f'ing identify myself and then he said, "Well, you know who I am." And I asked him, I said, "Are you Whitey Bulger?" He said, "Yes."

Scott Garriola: Just about that moment, someone catches my attention from a few feet away by the elevator shaft.

It was Janus Goodwin from the third floor, going to do her laundry.

Janus Goodwin: And I said, "Excuse me. I think I can help you. This man has dementia, so if he's acting oddly, you know-- that could be why."

Scott Garriola: Immediately what flashed through my mind is, "Oh, my God, I just arrested an 81-year-old man with Alzheimer's who thinks he's Whitey Bulger. What is he gonna tell me next, he's Elvis?" So I said, "Do me a favor, this woman over here says you have a touch of Alzheimer's" and he said, "Don't listen to her, she's f-ing nuts." He says--"I'm James Bulger."

A few minutes later he affirmed it by signing a consent form allowing the FBI to search his apartment.

Scott Garriola: As he's signing he says, "That's the first time I've signed that name in a long time."

Steve Kroft: There was a sense of resignation?

Scott Garriola: I don't think he had it. I did ask him, I said, "Hey, Whitey," I said, "Aren't you relieved that you don't have to look over your shoulder anymore and, you know, it's-- it's come to an end?" And he said, "Are you f****n' nuts?"

But in some ways Whitey Bulger and Catherine Greig had already been prisoners in apartment 303, which appeared to be a mixture of the murderous and the mundane. Alongside the weapons and all the money, they had stockpiled a lifetime supply of cleansers, creams, and detergents. The FBI took special interest a collection of 64-ounce bottles with white socks stretched over the top.

"I did ask him, I said, 'Hey, Whitey,' I said, 'Aren't you relieved that you don't have to look over your shoulder anymore and, you know, it's-- it's come to an end?' And he said, 'Are you f****n' nuts?'"

Scott Garriola: I said, "Hey Whitey, what are these? Are these some kind of Molotov cocktail you're making?" He goes, "No," he said, "I buy tube socks from the 99 Cents Store and they're too tight on my calves and that's the way I stretch 'em out." I said, "Why you shopping at the 99 Cents Store? You have-- half a million dollars under your bed." He goes, "I had to make the money last."

Its been said that one of the reasons it took so long to catch Whitey Bulger, is that people were looking for a gangster, and Bulger, whether he liked it or not, had ceased to be one.

Phil Torsney: He said it was hard to keep up that mindset of a criminal. And that's part of the reason he came down to that garage. It was hard to stay on that edge, that criminal edge, after being on the lam as a regular citizen for 15 years.

The master manipulator gave credit to Catherine Greig for keeping him crime-free, hoping it would mitigate her sentence. She is now serving eight years for harboring a fugitive. On the long plane ride back to Boston, Bulger told his captors he became obsessed with not getting caught, and would do anything to avoid it, even if it meant obeying the law. Whitey Bulger's biggest fear, they said, was being discovered dead in his apartment - and he had a plan to avoid it.

Phil Torsney: If he became ill and knew he was on his deathbed. He'd go down to Arizona, crawl down in the bottom of one of these mines, and die and decompose. And hope that we would never find him and still be lookin'-- lookin' for him forever.