A Bethlehem man who's charged with raping five teenage girls says a sexual addiction made him do it. Two of the alleged victims were pregnant. David Martinez is being a called a serial rapist.
But what may be inside the mind of an alleged serial rapist like Martinez?
Perhaps no on knows serial criminals better Dr. Katherine Ramsland.
"They are following through on what turns them on. what is exciting to them," said Ramsland.
Ramsland has written several books about serial criminals, including sexual predators.
What about the case of David Martinez -- the Bethlehem man that investigators say is a serial rapist.
Although she hasn't examined him, she says she can explain some of the behavior found in court records.
Martinez is charged with raping five teenage girls-- two of whom were pregnant.
"The pregnancy actually makes them more vulnerable. If they are afraid and they are protecting their unborn child, he knows that they will probably go along with what he wants," said Ramsland.
She says for a sexual predator -- or serial rapist -- it's not about sex, but about control and ego.
"Addiction to power and the feeling of it's kind of an ego inflation.' Look what I am getting away with,'" said Ramsland.
In Martinez' case, court records show he found most of the girls on Facebook, texted with them and then raped them when they met.
Martinez told police he can't control himself because he has a sexual addiction.
Ramsland says she doubts that claim. She says sexual predators usually do not act on spontaneous impulses, but a pattern that they know has worked in the past.
"A predator only sees pawns in his game essentially. Only sees people as ways to get what he wants," said Ramsland.
Ramsland says while there are some effective cognitive therapies, right now there is no single treatment that will definitively cure or stop a sexual predator.