An apparent large-scale operation Friday night tied to the disappearance of 84-year-old Nancy Guthrie marks a “significant escalation” in the Arizona case, with investigators now racing to canvas neighborhoods and fast-track critical DNA evidence, according to a retired FBI agent.

Acting on a lead, the Pima County SWAT team and the FBI on Friday executed a federal search warrant at a Tucson-area home roughly two miles from Guthrie’s home, detaining three people.

A fourth person was detained in connection to the warrant following a traffic stop in a Culver’s restaurant parking lot in Tucson, and a gray Range Rover was searched and towed from the parking lot.

Jason Pack, a retired FBI supervisory special agent with more than two decades of service, told Fox News Digital the developments have the “hallmarks of agents acting on specific, actionable intelligence.”

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However, Pack noted the real investigative work is just getting started.

While the searches and interviews were ongoing Friday night, Pack said other teams of agents and analysts were likely already planning a full neighborhood canvas around the location that was searched.

“They’ll be going door to door, looking to talk face to face with neighbors,” Pack said. “They want to identify patterns of life for each of the people detained. … It will help corroborate or dispute whatever those who were detained are telling agents right now. If someone says ‘I wasn’t home that night,’ a neighbor’s Ring camera might tell a different story. Investigators are building the box.”

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Aside from canvassing the area, Pack said the most pressing concern is likely processing new evidence collected from at least two scenes Friday night.

“DNA that doesn’t belong to Nancy Guthrie or anyone close to her has already been identified at her property. Gloves have been recovered. Now you’ve got whatever was inside that Range Rover that warranted agents draping it with a tarp before the cameras could see,” he said. “All of that evidence needs to get to a lab.”

Pima County Sheriff Chris Nanos recently defended his department’s use of a private Florida lab to process evidence in the case, telling Fox News earlier this week the FBI agreed it was best to continue with the contracted business rather than transfer the evidence to the FBI’s comprehensive crime lab in Quantico, Virginia.

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However, Pack stressed the situation is a race against the clock.

“Here’s the question. Do they wait until Monday to commercially ship it to a private lab? In past high-profile cases, I’ve seen FBI aircraft used to immediately shuttle evidence to the FBI Laboratory at Quantico,” he said. “That eliminates days of waiting. In a case involving a vulnerable 84-year-old woman who is without her heart medication, where every hour matters, you don’t wait for FedEx on Monday morning.”

Pack reiterated that in a time-sensitive case, authorities cannot afford to lose a weekend debating how to process evidence.

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“That decision should have been made days ago. Which lab, which courier, what’s the turnaround,” he said. “If the FBI has the lead, Quantico is the logical answer, and I’d expect evidence to be wheels-up before the sun sets today.”

Authorities have not yet confirmed if the newly obtained evidence will be flown to the private lab or Quantico, or when it will take flight.