Nancy Grace

Dave Mack, Dave Mack, an 84-year-old mother-grandmother is missing.

Words matter.

Words matter.

Straight out to Brian Fitzgibbons joining us, Director of Operations, USPA, Nationwide Security.

I can't say it enough.

He leads a team of investigators around the world finding and extracting missing people, including extractions from Mexico.

former Marine Iraqi War vet.

Brian, I would expect this is SOP.

I would be surprised if they didn't start.

Well, not Nanos, not Nanos, but the FBI didn't start looking at the HVACs, the electricians, the roofers.

Day one, we've heard about landscapers and pool guys, but now we're hearing specifically about HVAC workers.

Scott Eicher, founding member of the FBI Cellular Analysis Survey Team, CAST,

former FBI agent before that, former homicide, Norfolk, Virginia, 20, 12 years now with precision cellular analysis experts.

Iker, don't you think the FBI zoomed in the moment they got there and started looking at, well, we know looking at pool guys and looking at landscapers, but now

HVAC workers.

We also know they looked at electricians, but now we're learning more about roofers and HVAC workers.

Why?

We're just learning tonight that it's not just electricians, not just the pool guy and the landscaper, but specifically roofers and HVAC workers under the microscope.

And Susanna Ryan joining us, lab director, forensic DNA analyst at Pure Gold Forensics.

She is a consultant at Ryan Forensics, 25 years in the business of DNA and serology.