Tucson, Arizona - A retired FBI special agent thinks that a tattoo may be critical for identifying a mysterious suspect in the still unsolved Nancy Guthrie kidnapping case.

Six weeks after she disappeared from her home in Tucson, Arizona, the fate and location of NBC host Savannah Guthrie's mom remain unknown.

On of the few clues in the case was provided by security footage showing a masked and armed man at Nancy Guthrie's home in in Pima County, Arizona.

The so-called "porch guy" accidentally revealed a tattoo on his wrist, something that ex-Fox News host Megan Kelly brought up when talking with former FBI special agent Jonathan Gilliam on Wednesday.

"It could be a lot of things," Gilliam said. "That's the problem, Megyn, with all this evidence: it is speculation. And Nancy Grace likes to pump things up quite a bit."

"I don't know how he got that from that wrist. I don't know how he came out with that part of it."

He did, however, admit that the ink could certainly be used by the Pima County Sheriff's Department and the FBI to track down a more useful lead.

"Even that little bit right there, if somebody has been arrested and they have tattoos, they're going to have their tattoos recorded," he explained.

"So there could be a database that recognizes that portion. And somebody just has to put that together."