Remains found in the desert just miles from Nancy Guthrie's home sparked immediate speculation Monday about whether they belong to the 84-year-old, who's been missing for seven months – but authorities say there's no indication they're hers.

The Pima County Sheriff's Department declined comment to CNN about who found the remains, when they were located and why officials indicated there was no immediate link to Guthrie, whose disappearance in January has produced few public leads despite intensive search efforts.

However, authorities do not believe there is a connection between the remains and Guthrie's disappearance, a senior law enforcement official briefed on the investigation told CNN. The FBI referred questions to the sheriff's department.

"There may be practical law-enforcement concerns behind their silence," CNN Chief Law Enforcement and Intelligence Analyst John Miller said. "Saying that they don't believe there's a connection and officially ruling one out are two different things. The first requires an investigative judgment based on what they see, but the second requires actual scientific evidence."

The condition of the remains could complicate that evidence.

With a complete set of remains, Miller said, a forensic pathologist could determine fairly quickly whether the bones belonged to a male or female, and if not, that task could prove more difficult.

Environmental factors, including the effects of extremely high temperatures, direct sunlight over extended periods and animal activity could also play a role, Miller said.

"Authorities understand that ruling out a connection before they are certain would only draw more criticism to a case where they have already heard their share," Miller said.

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Sheriff's deputies were seen Monday at the reported location of the remains, on a hillside covered in saguaro cacti overlooking a busy four-lane highway in southwest Tucson.

It is a residential area, just on the outskirts of the city limit, one turn off a road called Ajo Way that leads to a handful of homes with long driveways.

From the highway, at least three sheriff vehicles were seen parked at the top of a residential driveway. The road leading up to the hill had a wooden sign marked "private drive."

Although there didn't appear to be a large law enforcement presence, at least three deputies could be seen hiking up into the hills of the northern batch of homes.

Guthrie, the mother of NBC "Today" show host Savannah Guthrie, vanished from her Tucson-area home February 1.

She was last seen January 31 before she was apparently kidnapped from her home in Arizona's Catalina Foothills — without her phone or critical medications.

In July, almost six months after Nancy Guthrie went missing, officials released the full contents of a ransom note and a follow-up letter addressed to her family, which claimed she had died, in hopes of generating new leads.

Investigators also continue to run lab analyses on DNA found at Nancy Guthrie's house.

Savannah Guthrie, who continues pleading for information through social media posts, and her family have offered a $1 million reward for intelligence that could lead to Nancy Guthrie's recovery.

This story has been updated with additional information.

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