Today, 340 years ago, in the year 1680, the following episode happened in Hildesheim, Lower Saxony, Germany. A member of the Jewish Community sent a young boy riding on a pony to the river to quench the pony’s thirst. His friends ran after the pony, teasing him with sticks. Eventually, another child got too close, the angry pony kicked him badly in his heart. Sadly enough the young boy died, half an hour later from his wound.
The story was presented to the local rav, Rabbi Elyakum Getz and he was asked who is at fault and how should the guilty one do teshuva? The rav paskened, that the one riding the pony is at fault. After his Bar Mitzvah, he should go with a minyan to the gravesite of the killed boy. With a crying voice, he should ask for forgiveness. He should go on a weekly basis for a one-day in galus, walking around in the fields barefoot. The very first year, every Erev Rosh Chodesh he should confess before three adults, and receive malkos. He should fast a whole year and do teshuva, and this he should do every year on the yahrzeit as well.
Source: Even Hashoham 45