President Donald Trump on Friday commented on why the FBI has not taken over as the lead agency investigating the disappearance of Nancy Guthrie nearly two weeks since she vanished from her Tucson, Arizona, home.

Guthrie, the 84-year-old mother of NBC host Savannah Guthrie, went missing from her home Feb. 1, and no suspects or persons of interest have been publicly named by authorities 13 days later.

While speaking to reporters at the White House, Trump explained why the Pima County Sheriff's Department remains the lead on the investigation. 

"They didn't want to let go of it, which is fine. It's up to them. It's really up to the communities," Trump told reporters outside the White House Friday afternoon. "But ultimately, when the FBI got involved, I think, you know, progress has been made."

White House press secretary Karoline Leavitt had said earlier that FBI Director Kash Patel assured her that the bureau was on the ground in Arizona and is offering local authorities the "full resources" of the federal government.

The president's comments came after a U.S. law enforcement source told Fox News Digital on Thursday that Pima County Sheriff Chris Nanos is blocking the FBI from key evidence.

During an interview Friday with Fox News' Matt Finn, Nanos defended his department's partnership with the FBI, saying his office did not find a glove at Guthrie's property and a private Florida lab, which the sheriff's department has been contracted with for decades, began receiving evidence at the start of the investigation and that the FBI agreed that evidence should continue to be sent there instead of the FBI's national crime laboratory in Quantico, Virginia.

Nanos added he called the FBI for assistance on the next working day after Guthrie's disappearance and that it would be "absolutely crazy" to not take advantage of their partnership.

Officials also specified the brand of backpack the suspect was seen wearing in a video released Tuesday, confirming it was a black, 25-liter "Ozark Trail Hiker Pack" backpack.

Trump was also asked Friday whether cartels or possibly another "nation state" could be involved in Guthrie's disappearance.

"You can't say that yet," Trump said outside the White House, responding to a question from Fox News' Jacqui Heinrich. "It's a little bit early."

"But it's somebody [who] either knew what they were doing very well, or they were rank amateurs. Either way, it's not a good situation," Trump added.