LOS ANGELES, United States (AFP) — The family of the kidnapped mother of a top US TV news anchor made a new plea for information from her captors on Thursday, after investigators said they believed the 84-year-old was still alive.

Nancy Guthrie, mother of NBC News “Today” co-host Savannah Guthrie, is believed to have been kidnapped from her home in Tucson, Arizona, some time on Saturday night or Sunday morning, sparking a massive hunt in a case that has gripped America.

“Whoever is out there holding our mother, we want to hear from you,” the missing woman’s son, Camron Guthrie, said in a video posted on Instagram.

“We haven’t heard anything directly. We need you to reach out and we need a way to communicate with you so we can move forward. But first we have to know that you have our mom.”

Savannah Guthrie had tearfully pleaded with kidnappers to share proof of life earlier this week.

The family’s renewed call came after the Federal Bureau of Investigation (FBI) disclosed that a first deadline of 5 p.m. on Thursday was made in a ransom letter, without providing a time zone.

FBI Special Agent in Charge Heith Janke told a press conference that a second demand of a payment by Monday was given in the letter.

“If a transfer wasn’t made, I think a second demand was for next Monday,” he said, declining to provide any information about what was threatened if the deadline was not met.

Janke added that the letter called for an undisclosed amount of money.

Authorities said they believed the missing woman was still alive, and said blood discovered on her doorstep belonged to her.