Police
There were 6 tapes in there. 5 had labels, but there was one that had none. They started thinking if there could be someone behind all of these and is playing a game on them. Since things were getting out of hand, they decided that it was time to involve the authorities.
The Curiosity
The couple was so curious wondering what could be on those tapes, so he got the tapes and watched them. After seeing what was on the tapes, he immediately called the cops and asked them to be in their house as soon as possible.