This incident wasn't witnessed by me, but rather by my mother. It is taken word for word from her account.

My paternal grandfather died in 2014. As per our custom, we arranged the funeral and mourned for 11 days afterwards. This took place on the 3rd or 4th day.

My mother and a few other women in my family were arranging for the ceremony in which his spirit would be put at peace. It was going to take place on the rooftop, and after the puja, there would be a meal. My mother was talking with the caterer on the rooftop and making arrangements. After they left the rooftop, my mother bolted the door shut behind her. There was no one else on the rooftop.

About an hour later, there was a strange severe knocking sound on the door of the rooftop. One of my aunts suggested that it was the wind knocking something against the door, but this theory was denounced, for it was a sunny windless day and the rooftop had been covered. Just then the knocking noise sounded again, and it was louder than before. The knocks were intermittent and irregular, and faded away after about half an hour.

My mother says that it was probably the spirit of my grandfather wishing to come in and meet his relatives one last time... No one is sure what it was though, and today my mother is also uncertain of the details.I believe in them, but as many ghost stories are, there are many skeptical people who claim that those who narrate these stories are lying. These stories are taken as an account from the parents and though the details have faded over the years, the gist of these stories are clear.

Another incident took place during the puja. Nearing the end, the priest requested us to close our eyes and pray. All I remember of the event is of a strange giddiness, but according to my parents, they saw my grandfather before them, albeit slightly blurrily.