Confession: A California man admits he sent fraudu...

Derrick Callella; Nancy Guthrie.Credit : California Department of Motor Vehicles; Nathan Congleton/NBC via Getty

A California man has pleaded guilty to sending fake ransom notes in Nancy Guthrie’s abduction case.

Derrick Callella of Hawthorne, Calif., pleaded guilty to two counts of harassment using a telecommunication device, the U.S. Attorney’s Office for the District of Arizona announced on Thursday, July 2.

Officials said that Callella, 42, admitted to calling and sending text messages regarding a bitcoin transfer to Guthrie’s family on Feb. 4.

“Callella acknowledged that he knew an earlier ransom demand had been made. Callella also admitted that his actions were meant to harass the family by seeking information about the investigation into the missing person’s disappearance,” the U.S. Attorney’s Office said in its press release.

Callella faces a maximum sentence of two years’ imprisonment, a $250,000 fine, or both, plus one year of supervised release. He is set to be sentenced on Sept. 10.

Guthrie, the 84-year-old mother of TODAY host Savannah Guthrie, was abducted from her Tucson, Ariz., home in the early morning hours of Feb. 1, and in the months since, no official suspects have been identified.

On Wednesday, the FBI announced that there have been “several ransom notes” over the course of the investigation into the kidnapping of Nancy, some of which haven’t yet been ruled out.

The FBI’s Phoenix office said that while some of the notes “have been deemed to be extortion attempts without legitimacy,” other ransom demands “may potentially be legitimate and are still being investigated as such.”

Savannah Guthrie and mother Nancy Guthrie.

Savannah Guthrie/Instagram

The official statement came after a Reuters report claimed the ransom notes were fake, citing an FBI source with knowledge of the case. This includes the two ransom notes received in February shortly after Nancy’s disappearance as well as the note recently received claiming to know the identities of Nancy’s kidnappers.

The FBI official said that the first two ransom notes were determined to have come from the same sender, according to the Reuters report. The first note was sent to TMZ and demanded a sum in the millions in cryptocurrency. The second note claimed that Nancy had died shortly after being abducted, NBC News previously reported.

Nancy’s case “continues to be investigated as a kidnapping for ransom case,” according to the FBI.

Nancy was last seen at her Arizona home at approximately 9:30 p.m. local time on Jan. 31, according to the Pima County Sheriff’s Department. She was reported missing the following day after she failed to show up for a virtual church service, PEOPLE previously reported.

One of the latest updates in the investigation came in May, when Pima County Sheriff Chris Nanos told PEOPLE that investigators were awaiting potential breakthroughs from DNA testing while continuing to analyze digital evidence in hopes of generating new leads.