<s>[INST] Here's an mystery story with many loose ends. I'm going to ask you a series of questions based on the clues. I'll piece the story together and try to find the solution. Let's start with the story:

Detective Jameson sat in his office, staring at the case file on his desk. The Smith family, consisting of parents John and Emily, and their two children, Michael and Sarah, had gone missing. Their disappearance wasn't reported until six days later, when a neighbor noticed their front door was open and their cars were still parked in the driveway.

Upon investigation, the police found a suspicious letter in the house. The letter was typed on a computer and printed, but the computer was found still running, with the draft of the letter still open on the screen. The letter read: "Don't look for us. We are safe. We were in danger and we left quickly. We will contact you soon." The letter was unsigned, but it seemed to be written by the Smith family.

The detective examined the house and noticed that the family seemed to have left in a hurry. There were dirty dishes in the sink, and a meal was partially cooked on the stove. It looked like they left during dinner. The police found a piece of torn fabric caught in the front door, which seemed to be from a jacket or a coat.

The next day, the police received a message from an unknown number. The message read: "Stop looking for us. You won't find us." The message seemed to be from the same person who wrote the letter.

The detective was confused. The letter and the message seemed to indicate that the Smith family had left voluntarily, but the signs in the house suggested they had been taken. He was also puzzled by the piece of torn fabric caught in the door.

Now, let's start piecing together the story. 
My first two questions are:

1. What could the piece of torn fabric mean?[/INST]