The 16th Karmapa passed a sacred letter of his next life reincarnation prediction to his disciple in 1981 and was asked to open in year 1991.
The sacred letter clearly stated the names of his next life's father and mother, the description of the place he would be reborn, the phenomenon when he was born and the year he would be reborn.
When his disciples went to search for him, he was only about 7 years old and he knew when his disciples was coming to look for him. He was all dressed up and sitting in his house waiting for the arrival of his disciples.
This is just amazing!
Followings are the videos on the sacred letter and the searching process.