We have seen a murdered and taken videos

My son arranged a tour to a hill side. Whenever he goes out of station he will take the camera with him. This time it is very painful for him, most of the time it is helping to others. It is useful not only for taking videos Why I’m telling like this, One time this camera zoom lens showed a murderer he killed his wife with the knife. When we saw this through camera lens and taken videos, the same time the murderer also watch us. He followed and threaten us to give all videos what we have taken. This is the only proof and identification to police for that murder. Immediately we escape from that place and go to the nearest police station handed over all the evidences. The police has arrested him and give him punishment.