New York, New York - TV news host Savannah Guthrie, whose mother was kidnapped in February, said Tuesday she is in "agony" after reports the elderly woman died shortly after being abducted.

Guthrie, the anchor of NBC's Today show, pleaded for anyone with information about the disappearance of Nancy Guthrie (84) to contact authorities.

"I wanted to just take the opportunity to ask people, to really... to beg people to come forward, somebody knows something," she told viewers.

"This is a news story today that is on your radar, but this is the life that my sister lives, that I live, that my brother lives, that our extended families live, that our children live every day, and we are in agony, we cannot be at peace.

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"This is a moment to tell you that we need your help."

Guthrie's emotional appeal came after US media reported that one of two apparently credible notes sent to the family in the weeks after Guthrie was kidnapped indicated she was dead.

The first note had demanded millions of dollars in Bitcoin for her safe return, while the second said that she had died.

CNN reported the note indicated the kidnappers had not intended to kill her.

The February 1 kidnapping in Tucson, Arizona, made headlines and went viral on social media.

Interest intensified when security camera footage released by authorities showed a masked, apparently armed man at the house, which lies in the desert suburbs of the city.

Savannah Guthrie has previously offered $1 million for a tip leading to the recovery of her mother, while the FBI has offered $100,000 for information.

"We're begging for your help," she told viewers again on Tuesday, shortly before a tipline number was displayed on screen.

"Please, if you're watching, no matter how small... the reward is there. You can tell us, it can be anonymous," she said.

"Please do the right thing for us, for our family, for our children, and we love our mom, and we'll never stop looking for her, never."