A crime has been committed in a town of 100,000 inhabitants. The police are looking for a known number of perpetrators, believed to live in town. DNA evidence is found on the crime scene. Kevin's DNA matches the DNA recovered from the crime scene. According to DNA experts, the probability that a perpetrator matches the crime scene DNA is 100%, and that a random person's DNA matches the crime scene DNA is 1 in 10,000. Before the DNA evidence, Kevin was no more likely to be the guilty person than any other person in town. The probability that Kevin is one of the perpetrators after the DNA evidence appeared is at least 50 % (taking the number of perpetrators into account). At least how many perpetrators are there