BREAKING NEWS: FBI ANNOUNCES “MAJOR TURNING POINT” IN NANCY GUTHRIE CASE — Search teams abruptly retreated after ground radar detected a disturbing object under a tree in Nancy’s yard

Jonathan Wackrow, a former Secret Service agent under President Obama, told CNN’s Wolf Blitzer that the latest request for neighbors to review their surveillance footage could lead to “a real break in the case.”

Wackrow, now a security consultant, said the specific dates noted in the request “signal that (investigators) have reason to believe that something relevant happened on that day.”

Law enforcement might be looking to see if someone surveilled Guthrie’s home prior to the kidnapping or if someone was “boundary probing” by testing to see if there were restrictions to entering the property, Wackrow said.

“They’re trying to see, ‘Was there a person there before the attack?’” he said, but added any footage shared by neighbors is not likely to yield a “smoking gun.”

“We may see a sliver of a vehicle in one video that they can then tie to another video,” Wackrow said. “This is going to be a patchwork of video evidence put together.”

But he added the request alone can also indicate “the investigation is moving forward and it’s becoming more precise.”

Savannah Guthrie posted a clip Thursday of an old home video and a family photo to Instagram in tribute to her mother, Nancy Guthrie, who remains missing after 12 days.

The video in the new post appears to show Savannah and her older sister Annie Guthrie – as children dressed in matching outfits – joining their mother who is sitting on a bed of flowers. The young girls smile as they hand their mother purple flowers, taking turns smelling the petals.

A photo at the end of the post seems to show Nancy flanked by all three of her children – Camron, Annie and a baby Savannah sitting in her mother’s arms.

“our lovely mom. we will never give up on her. thank you for your prayers and hope,” Savannah Guthrie wrote in the caption of the post.

This post has been updated to include additional information.

A tent is seen outside of Nancy Guthrie’s home in Tucson, Arizona, on Thursday.

CNN

A white tent was put in place directly outside the front door of Nancy Guthrie’s Tucson home Thursday morning before being taken down shortly afterward, according to CNN’s Leigh Waldman, who is on the ground in the area.

The tent was put up just before 8 a.m. local time. A reporter asked the investigators which agency they were with, but the men did not answer.

Investigators were also seen packing up a large black case along with other items they had brought into the home.

Investigators pack up items from Guthrie’s home on Thursday.

In addition to a Pima County Sheriff’s Department vehicle in front of the home, two additional unmarked vehicles were also parked in the driveway.

Remember: Blood stains found on the porch – which officials have confirmed belong to Guthrie – suggest ways her kidnapper may have left traces behind, a forensic expert tells CNN, giving investigators more insight into what may have transpired.