One pfennig coin

In 1953 and 2019, the corpses of children are found in Winden. They are all wearing a red twine necklace with a one pfennig coin hanging on it.The date minted on the coin: 1986. The police are baffled.

Helge and the twine necklace

SPOILER ALERT!

In 2019, Ulrich finds a one pfennig coin on a red twine necklace on Helge Doppler’s nightstand in the nursing home. He takes it along and follows him to the cave. Ropes of red twine guide him to the shaft and then to the year 1953. Who put them there?

In 1953, Ulrich encounters Helge as a little boy. He shows him the coin. Helge doesn’t recognize it – but he keeps it. Later, when he is displaced into 1986, the boy takes it with him.