Hair found in the Arizona home of Nancy Guthrie is not linked to any potential suspects in her disappearance, federal law enforcement officials said Thursday.

In a brief statement, the FBI’s Phoenix office said that “all hair had been resolved and it does not point to a suspect” in the investigation.

The bureau declined further comment.

Pima County Sheriff Chris Nanos told NBC News that the hair had no DNA on it.

“To find DNA on hair is extremely rare,” he said. “Hair doesn’t produce DNA like touch DNA or bodily fluids.”

The announcement came six months after the 84-year-old mother of “TODAY” co-host Savannah Guthrie disappeared in what federal authorities have described as a kidnapping-for-ransom case.

In a July 1 statement, the FBI said it had received several ransom notes, including some that may be potentially legitimate, since Guthrie was reported missing on Feb. 1. Others were described by the agency as illegitimate extortion attempts.

The FBI said it is still investigating some of those demands. Earlier Thursday, the Pima County Sheriff’s Department said the investigation is active and ongoing.

In an Instagram post Monday, Guthrie posted a message pleading with the person who may have taken her mother to “tell us where to look for her.”