Michael David Barrett has not been charged in the other cases but attorney Marshall Grossman told "Good Morning America" in an exclusive interview that he may have posted as many as 40 videos of other women.
"We have credible, determined evidence that Mr . Barrett did the same thing, not just with Erin, not just with a few others, but with 17 other women," he said. "Most of the rest of them have no idea their images were taken."
Michael David Barrett, a former Illinois insurance executive, pleaded guilty Tuesday to interstate stalking after admitting he secretly taped and then tried to sell nude videos of Andrews shot while she was in hotel rooms.
He could face up to five years in prison but in exchange for his plea, Barrett reportedly would spend no more than 27 months behind bars. Sentencing is scheduled for Feb. 22.
Andrews, Grossman said, will focus on making sweeping changes in the hotel industry.
"She wants the hotel industry to see this as a wake-up call," Grossman said, calling for at least "minimal protection in order to help secure the safety and privacy of their guests.
"Thus far, the industry has been rather lax in doing that."
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Andrews, 31, spoke in a blistering statement in the courtroom Tuesday, telling a federal judge that Barrett was a sexual predator who should "never see the light of day."
After the hearing, Andrews said, "I lost it for the first couple of minutes. I couldn't really keep it together, but I wanted to go in right away because I just wanted to get it over with and just see him."
Barrett's attorney issued a statement after the hearing saying, "He deeply regrets any pain he has caused to Ms. Andrews. At this time, Mr. Barrett looks forward to the future and any opportunity to make positive changes in his life."
That wasn't enough for Andrews.
"I want him to stay in jail as long as possible," she said. "He's a threat to women everywhere. I feel like it was my duty to come here and tell this judge what he has done to me, because I don't want another family to be ripped apart by this. I don't want somebody else's career to be ruined by this."
Erin Andrews Attorney: Hotel Guests Are Vulnerable Until Industry Changes
Police say Barrett made as many as eight separate videos and then posted them on the Internet starting in July.
Examination of a photo of one of the peepholes in a room where Andrews was taped shows obvious signs of tampering, Grossman said, in the form of gouge marks where the peephole had been popped out. He suggested hotel guests put a Band-Aid or a piece of tissue paper over the peepholes in their rooms, just to be safe.
He also called for better training for employees. It "boggles the mind," he said, that Barrett was able to learn where Andrews was staying and in what room without her permission.
"For now, most guests are vulnerable and the industry has to clean its act up," Grossman said.
Andrews told the court she is now routinely subjected to crude remarks by stadium crowds when she is on the job.
Her father, Steve Andrews, was by her side Tuesday.
"We have cried a lot, we talked a lot," he said. "There haven't been a lot of good times in the last several months."
The FBI said one of the occasions when Andrews was taped was in Nashville, Tenn., where Barrett requested to stay in the hotel room next to Andrews. Barrett is suspected to have taken videos from his cell phone through the peephole in the reporter's door. According to the criminal complaint, Barrett cut the peep holes ahead of time so he could remove them quickly and easily without making much noise once Andrews was in her room.
The second videotaping incident, officials said, took place in a Milwaukee hotel, although Barrett never checked into the hotel there.
Officials said Barrett then attempted to sell, via e-mail, the grainy videos to entertainment Web site TMZ.com, where an employee notified Andrews' attorney. The FBI said the e-mails were traced back to Barrett.
TMZ, which is based in Los Angeles, did not post the videos but they surfaced across the Internet on adult Web sites.
Stalker Caused Erin Andrews Massive FearInvestigators say Andrews suffered from anxiety and was always fearful that a stalker might be watching her. She even called 911 when the paparazzi camped outside her Atlanta home in July after the videos had surfaced.
"My last name is Andrews. I'm all over the news right now," she told the 911 operator. "I'm the girl that was videotaped without her knowing, without her clothes on in the hotel. ... They're looking at me through my window."
When the operator asked if she was OK, Andrews responded, "I did nothing wrong, and I'm being treated like ... Britney Spears."
Andrews has worked as a sideline reporter for ESPN's college football and college basketball broadcasts since 2004. The former sports dancer had amassed a large fan following even before the nude videotapes surfaced.
Some Web sites called her "Erin Pageviews" because of her popularity on the Internet, and Playboy magazine named her "sexiest sportscaster" in 2008 and 2009.
The videotapes caused a sensation on the Web, and Andrews topped Google's list of most searched terms for nearly a week in July, when the videos surfaced.
Andrews, who returned to work in September, told talk show host Oprah Winfrey she was horrified when she saw her nude videos posted on the Internet, and she feared her career was over.
"I opened up the computer and could feel my heart pounding," Andrews told Winfrey.
"I kept screaming, 'I'm done. My career is over. I'm done. Get it off. Get it off the Internet,'" said Andrews, recalling the phone call to her father when she first spotted the videos. "They thought I was physically injured, [that's] how bad I was screaming."
ABC News' Justin Weaver, Todd Conner, Eric Horng and Russell Goldman contributed to this report.