As the Guthrie family prays for the return of 84-year-old Nancy Guthrie, Callahan Walsh says, "We know what this family is going through."
"We know the not knowing is the hardest part," Walsh, the executive director of the National Center for Missing & Exploited Children, told ABC News' "Good Morning America."
The NCMEC was started by Callahan's parents, John and Revé Walsh, after Callahan's 6-year-old brother, Adam, was abducted and later found murdered.
Callahan Walsh said the Guthries need to remember that Nancy Guthrie's abduction "is not what defines her."
"She's a beautiful, beautiful human being who raised incredible children," he said.
"Law enforcement hasn't given up hope, the National Center hasn't, we haven't as the Walsh family. We know the Guthries haven't, either," he said.
Nancy Guthrie, the mom of "Today" show host Savannah Guthrie, was abducted from her Tucson, Arizona, home in the early hours of Sunday, Feb. 1.
On Tuesday, Savannah Guthrie announced a new $1 million reward for the recovery of her mom. Sources familiar with the family's decision told ABC News the family was prepared to fund the reward from the start, but waited because they were initially advised against it.
"Every hour and minute and second and every long night has been agony," Savannah Guthrie said in an Instagram video on Tuesday.
"Somebody knows," she said. "And we are begging you to come forward now."
The combined reward between the family and law enforcement now stands at $1.2 million.
Separately, the Guthrie family is donating $500,000 to the NCMEC to shine a light on other missing persons cases.
The donation "makes a huge difference," Callahan Walsh said.
"They've turned their heartbreak into a commitment of generosity," he said of the Guthries. "This will go on to help elevate missing children's cases, get attention on cases that may not be getting the attention they deserve. This will go to help support families and bring home more missing children."
Authorities ask anyone with information about Nancy Guthrie to call 911, the FBI at 1-800-CALL-FBI, or the Pima County Sheriff's Department at 520-351-4900.
