Attorney Marshall Grossman said that the media outlet, which he did not identify, had received at least a dozen e-mails since September threatening Andrews and passed them to her representatives Thursday.
The e-mails were at first sexual, but the most recent were explicitly violent and "threatened Erin with murder," Grossman said. They also had details about location and method.
The messages discuss the case of Michael David Barrett, who was sentenced last month to 2 1/2 years in federal prison for secretly shooting nude videos of the ESPN reporter.
"He refers to Barrett in his e-mail in a way to make clear to us that situation had some influence," Grossman said, but added that the man appeared to have no ties to Barrett.
The FBI has been notified, Grossman said. He said the man's identity is known to law enforcement and is believed to live on the East Coast. An e-mail message left for an FBI spokeswoman was not immediately returned.
Andrews is not yet seeking a restraining order but has asked ABC to beef up its security on "Dancing with the Stars," Grossman said.
Private security also has been hired to protect Andrews and her family.
Andrews has no plans of quitting the show.
"She's not the type to be easily threatened," Grossman said. "She has every intention to meet her obligations."