WATCH: Closing in on the brutal killer in DC mansion murders: Part 3

WATCH: Closing in on the brutal killer in DC mansion murders: Part 3

Transcript for Closing in on the brutal killer in DC mansion murders: Part 3

??? Lean on me… ??? Police are on the scene of a deadly house fire. Four people found dead inside. Reporter: If the fire at 3201 woodland drive in Washington, D.C., had burned faster. If the Washington, D.C., firefighters had responded a little slower, the key evidence in the case might have been destroyed. But the location of the crime, the nation’s capital, gives authorities a special advantage. This is Washington, D.C. We’re unique in that sense. Our metropolitan police department and our D.C. Fire department is backed up by federal agencies. Reporter: The arson task force at the mansion includes the ATF, which boasts perhaps the one lab in the country best equipped to extract DNA from fire damaged evidence. Greg zaranopas is the deputy assistant director who runs the lab. Reporter: Typically, we’re looking at debris from a fire scene. Reporter: This is where that strange delivery, the domino’s pizza, and those discarded pieces of crust comes back to bite the mansion home invader. A slice of pizza crust broke this case wide-open. Reporter: Crime scene specialists recover the leftover crusts. Nothing more than household garbage to you and me. But for them, the perfect serving of prime evidence. They rush the crust to the ATF lab, working around the clock. Looking at food, when someone takes a bite of it, we can see if there’s any DNA present. Reporter: Todd bill, an ATF analyst, lifted the DNA profile off that pizza crust. If there’s something, like, in this situation, where there’s a violent offender, we can call the FBI and they will do an immediate search for that profile. I have never seen a DNA hit turned around that quick. Never. Reporter: Tuesday, may 19th, only five days after the fire and the murders, a breakthrough. Boom. They get a hit. We’ve got a name. We’ve got a face. Reporter: Daron Wint, 34 years old. Because of that lengthy, criminal record, his DNA was on file. And now we knew at least one person who was allegedly inside that house. Reporter: Now all they have to do is find him. Thus begins an intense, 48-hour nationwide manhunt. Reporter: Robert Fernandez with the U.S. Marshals service is part of the task force now hunting for Wint. We try and draw a picture of relatives, locations where he’s lived, friends, patterns of life. Reporter: Then, Wednesday night, exactly one week after the family had been taken captive in their mansion, authorities get a line on Wint. We were able to determine that he had fled the D.C. Area. Two days after he commits these murders, Daron Wint takes a road trip. And he goes to New York, of all places. He gets on a bus and goes to his fiancee’s apartment. And took her on shopping sprees, paid off her credit cards, all the while paying with $100 bills, always $100 bills. And so while D.C. Police are looking for the killer of these three adults and a child, Darren Wint is living it up in New York City. They’re sitting in bed together in her New York apartment and see his face come on the news. He saw himself on the news, from what we understand. And then fled the area. Reporter: And you just missed catching him. That’s right. Eventually he takes a taxi, a $900 taxi from New York City to D.C., back to his father’s house and that’s where he and his brother concoct a plan. They’re gonna get a lawyer and they’re gonna turn him in. Reporter: But Wint’s brother and a cousin, who say they had nothing to do with the crime, begin plotting to deliver Daron to the police immediately. At that point the plan changes. And Daron isn’t aware the plan changes. Reporter: Thursday night, a week after the murders, U.S. Marshals track Wint to this Howard Johnson’s in the D.C. Suburbs. You’re going in ready for anything. That’s right. Reporter: And immediately, a surprise. The U.S. Marshals’ advance team notices Wint leaving the hotel. But he isn’t alone. That advance team radioed to us they had a suspicion that he was in one of two vehicles that were right over here. In one of those vehicles, Wint and three women. In the other, Wint’s younger brother, Darrell, and their cousin. At that moment, both of those vehicles left and turned northbound. Reporter: Didn’t see that coming. Not at all. But we’re ready to roll with it. Reporter: Air support is called in from prince George county pd. Authorities tail the group, now traveling in a two-vehicle caravan. A box truck with North Carolina tags, followed by a white Chevy Cruz. How many cars are following him at this point? Altogether, it could have been 25, maybe 30 vehicles. Reporter: Moments later, authorities spring the trap, employing a daring maneuver to stop the cars cold. It’s called a vehicle pin blocking maneuver. Reporter: The marshals’ cars surround the white Chevy and the box truck on all sides and on the commander’s go, the front car reverses, the rear car speeds forward, and four more cars surround the target vehicles on all sides. Basically, pinning the car at four points and immobilizing it. They were looking in their mirrors. They saw all the lights and they put their hands up. Reporter: Immediately. Immediately. I think they were completely and totally startled and surprised. Reporter: So this is where it happened. Yeah, right here. Reporter: In the rear passenger seat of the white Chevy — Daron Wint, trapped. He followed commands. He got out. He crawled. He got on the ground. He was immediately handcuffed. And brought over to a police vehicle and he didn’t say a word. It was the end of a painstaking 48-hour manhunt. No sleep. From D.C., to New York, back to the D.C. Area, and he’s now in custody. Reporter: In the car Wint was driving in police report finding clothing, an iPad, two knives, cash, and thousands of dollars of money orders. What did you see? In the truck, in the side compartment, a big wad of cash. Reporter: But the strangest find, a crumpled piece of paper. Scribbled on it, “300 Indiana avenue.” Which is the address for the headquarters of the D.C. Police. That may be another piece of information that would suggest the relatives are working with the marshals. Reporter: Wint appears in

This transcript has been automatically generated and may not be 100% accurate.

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