The FBI has arrested a Los Angeles man accused of sending ransom-related text messages to the family of missing Arizona woman Nancy Guthrie, authorities announced Thursday.

Fox News correspondent Bill Melugin reported that the texts were allegedly sent by Derrick Callella and were intended to see whether the family “would respond,” Mediaite reported.

Melugin emphasized that the messages are not believed to be connected to the primary ransom demand tied to Guthrie’s disappearance.

In a post on X, Melugin said federal investigators determined Callella used a VOIP application to send the messages, but were able to identify him through an emergency disclosure request to his mobile carrier, which led them to his IP address and California residence.

According to the criminal complaint, Callella sent the text messages on or about Feb. 4 “with intent to abuse, threaten, or harass any specific person.”

The New York Post reported that Callella, who is in his mid-40s, allegedly texted Guthrie’s daughter Annie and her son-in-law Tommaso Cioni about the missing woman.

One of the alleged messages stated, “Did you get the bitcoin were [sic] waiting on our end for the transaction.”

On Wednesday night, Today show host Savannah Guthrie and her siblings released a video publicly pleading for the safe return of their 84-year-old mother.

At a press conference in Arizona on Thursday, the Federal Bureau of Investigation confirmed that one individual had been arrested earlier that morning for allegedly writing a fraudulent ransom message for financial gain.

Heith Janke, special agent in charge of the FBI’s Phoenix division, issued a warning to others attempting to exploit the situation.

“My next message is to those impostors who are trying to take advantage and profit from this situation,” Janke said. “We will investigate and ensure you are held accountable for your actions.”

Also on Thursday, TMZ reported on an unverified ransom letter the outlet said it received earlier in the week.

TMZ editor Harvey Levin said federal authorities disclosed additional information about the letter during Thursday’s briefing.

“So, the FBI just revealed some things about the letter we received that we have not talked about yet,” Levin said. “That second deadline is Monday — they’ve just announced that as well. We’re not going to say what gets triggered on each deadline, but the first one, the demands change, and the second one is much more serious.”

Investigators are analyzing DNA evidence recovered from the Tucson home of missing 84-year-old Nancy Guthrie, sending it to a Phoenix laboratory as part of the ongoing investigation, authorities said Wednesday.

The biological samples were among items collected from Guthrie’s residence in the Catalina Foothills area north of Tucson, which law enforcement has treated as a crime scene in the search for the mother of “Today” show co-host Savannah Guthrie.

Law enforcement has not disclosed when DNA testing results might be available. Authorities said it could take months or even years to identify someone through DNA testing, but the method is very effective.

“Basically, what you’re trying to isolate is, A, is that her DNA, and B, is there a mixture or any foreign DNA that would indicate the perpetrator may have been injured while taking her,” Troy Hillman, a former homicide sergeant with Phoenix police, told 12News.

Hillman, who spent 20-odd years solving homicide cases that had gone cold, also noted that investigators can push urgent cases to the front of the line.

“Absolutely — especially when we believe she could still be alive and time is of the essence,” He said. “I think she needs her medication.”

Investigators have said Guthrie requires daily medication and has limited mobility, heightening concern for her welfare.

Pima County Sheriff Chris Nanos has said the scene showed signs of forced entry, and officials believe Guthrie was taken from the home against her will between Saturday night and early Sunday morning.