Drew Peterson, 54, recently proposed to his 23-year-old girlfriend of four months, his publicist confirmed to ABCNews.com, but he will not reveal her identity in an attempt to shield her from the media.
"Yes, Peterson is engaged," said Glenn Selig, Drew Peterson's publicist, who added the proposal occurred "in the past few days." "But we're not saying to who. He's entitled to his privacy and so is she."
The family of Stacy Peterson said that at first they were "shocked" to hear about Peterson's engagement.
"We were shocked when we first heard but then when we thought it through we weren't at all surprised," said Pamela Bosco, the spokeswoman for Stacy Peterson's family. "This is obviously a pattern we've seen with [Peterson]."
Bosco said that Stacy's family believes Peterson must have an ulterior motive for making his engagement public.
"If the engagement was really a private matter he wouldn't have made it public," said Bosco. "Maybe it has something to do with his legal situation or a book deal." In any case, she added, the family believes there must be an ulterior motive that involves money.
"I don't think anything he does right now is really about love," she said.
Asked whether the family had any advice for Peterson's fiancé, Bosco said that the mystery woman has enough information to make a decision about Peterson herself.
"It's not like she's walking into this blinded – there's a lot of information out there to help her make an intelligent decision," said Bosco. "Nothing I could say to her would change her mind."
And as for whether Stacy's family believes Peterson's bride is in danger, Bosco said she's concerned.
"If history repeats itself then I'd say this is not a good situation for her to be in," she said.
Drew Peterson garnered media attention after his wife, Stacy Peterson, 24, went missing Oct. 28, 2007. He was widely criticized for his blase attitude toward his wife's disappearance, even alleging to the press that his wife's PMS had led her to run off with another man.
The case remains open and is under investigation by the Illinois State Police and the Will County State's Attorney Office. A statement released by James Glasgow, Will County state's attorney, said, "I fully expect there to be a resolution in at least one of these investigations in the near future."
Drew Peterson told ABC News in an interview last year that the search for Stacy Peterson was a "waste of time."
On the anniversary of Stacy Peterson's disappearance, Drew Peterson told ABC's "Good Morning America" that he hopes she one day turns up.
"I hope someday she pops her head up and shows herself," he said.
Drew Peterson's legal troubles grew when the body of his third wife, Kathleen Savio, was exhumed and he was named a suspect in her 2004 death, which had initially been ruled an accident. Authorities now believe Savio's mysterious bathtub drowning was a homicide.
But because Drew Peterson is still legally married to Stacy Peterson, a divorce will be necessary before he can set a date to walk down the aisle with his mystery bride.
"He's legally married still," said Selig, "so I guess in order to get remarried he'll need to get a divorce first."