A student has pleaded guilty to hacking the computers of Miss Teen USA Cassidy Wolf and other women.Jared James Abrahams also admitted he secretly photographed them with their own webcams.
In Ms Wolf's case, he was able to take nude photos of her without her knowledge, authorities said.
He posted a naked photo of Ms Wolf online after she did not respond to him, it was claimed.
Abrahams and Wolf went to the same high school.
He was arrested on September 26 on suspicion of anonymously using malicious software to hack into webcams, take control of their computers and capture nude photos or videos, the FBI said.
Nineteen-year-old Abrahams, of Temecula, California, entered his plea in federal court in Orange County.
"I hacked several girls' computers and, using their webcams, took photos of them when they weren't aware," Abrahams said.
Over the past two years, he allegedly hacked into the computers of at least a dozen women in their late teens or early 20s from various states and countries, including Ms Wolf.
The computer science student faces up to 11 years in prison and fines of up to $1m when he is sentenced in March.
Abrahams is also accused of emailing the victims and saying he would publish the images of them on social media sites if they did not send him additional pictures or undress for him.
If the women complied, Abrahams promised to destroy the images.
At least two of his victims gave in to his demands, authorities said.
"Did you know you were extorting them when you made these demands?" US District Judge James Selna asked.
"Yes," Abrahams responded.
He told the judge he has autism and has been under treatment for it for the past 10 years.
Abrahams pleaded guilty to three counts of extortion and one count of unauthorised access of a computer.