Former police Sgt. Drew Peterson on Thursday denied any involvement in his fourth wife's disappearance on the same day his sons were expected to appear before a grand jury investigating the death of his third wife.

"I'm prepared for anything that should come up," said Peterson, a suspect in Stacy Peterson's disappearance, on NBC's "Today" show.

"It was kind of shocking" when a coroner reversed course last week and found the death of his third ex-wife, Kathleen Savio, to be a homicide, Peterson said.

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A medical examiner initially found that her death was an accident until investigators reopened the case and exhumed her body last fall.

Savio was found dead in her bathtub in March 2004, shortly before her divorce with Peterson was finalized. Four years ago, a coroner's jury ruled her death was an accident.

Savio told family members shortly before her death that she feared Peterson and thought he could make her death look like an accident.

"I controlled my family and I think more people in America should control their family," Peterson said.

Stacy Peterson, 23, was reported missing in October after she failed to show up at a friend's home. Her family believes that Drew Peterson is involved in her disappearance but he maintains his innocence and has not been charged with any crime.

Meanwhile, Peterson's two sons with Savio did not appear Thursday before a grand jury investigating the death of their mother. They are expected to appear at a later date.

Sources close to the Peterson investigation told FOX News' Greta Van Susteren that four police officers arrived at the ex-police sergeant's house at 9 a.m. Wednesday.

Peterson answered the door and they asked to see 13-year-old Christopher and 15-year-old Tom.

When they came to the door, police served them each with a grand jury subpoena.

Peterson reportedly was attempting to hire a lawyer for the two boys.

FOX News' Greta Van Susteren contributed to this report.