You know their name and address, and sometimes even their location. The predator is always one step ahead of its prey. After the predator rapes/assaults his victim, it is not uncommon for murder to accompany it. Philip Markoff would contact people on Craigslist asking to meet for one thing or another. As innocent as it may seem, he is also known as the Craigslist Killer. It's easy to trust a nice guy or girl online, but who are they really? There's no way to know, but people do it every day. Humans have become ignorant of the dangers of the world.