(CBS) — Six years ago today, Stacy Peterson disappeared from her home in Bolingbrook and her family is marking the anniversary.

It is all very personal and very private. There are no public vigils for the family of Stacy Peterson as they mark six years since she vanished – the fourth wife of Drew Peterson.

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“We will always know that he was what happened to her,” said Pamela Bosco, the spokeswoman for Stacy Peterson’s family.

Drew Peterson is in prison for the murder of his third wife Kathleen Savio and won’t be eligible for release until he’s in his 90s.

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“He should never be out again because we know now that another woman is going to be safe out there because that’s where he’s going to stay for the rest of his life.”

Pamela Bosco says the family believes Stacy is dead, but they’re still hopeful they will learn what happened to her some day.

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Illinois State Police say there are no new leads in Stacy Peterson’s disappearance.