Nanette Konig, Anne Frank's childhood friend, recalls their time together

One of Anne Frank's close friends is opening up about her final encounter with the young icon and the history of her diary.

National Geographic is airing the documentary "Anne Frank: The Nazi Capture," and lending her voice to the documentary is Frank's childhood friend Nanette Konig. The girls were classmates and Konig claims she was actually present when Frank received the diary that would eventually make her known across the globe.

"I went to her [13th] birthday party in June 1942 and that's where I first saw her diaries," the now 84-year-old told National Geographic. "I didn't know it but they went into hiding in July, because people didn't announce it. It was rumoured they had gone to Switzerland."

Of course, the Franks were hiding in a secret annex in Amsterdam.

The two friends would eventually reunite, but in much darker conditions. They'd reportedly see each other at the Bergen-Belsen concentration camp, though Konig says they were both skeletal.

"We did recognize one another and it was very emotional," Konig said. "It's really terrible. For me it's very hard to think that she died and I survived."

It would be the last time she saw Frank. Frank and her sister Margot died just weeks before the concentration camp was liberated.

Konig now travels to schools to tell her story. She feels she has an obligation to spread Frank's message.

"Anne Frank" The Nazi Capture" premieres Tuesday night at 8pm on the National Geographic Channel.

Watch a quick biography of Anne Frank:

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