Attorney Harry C. Smith, who also represented Peterson's fourth wife Stacy Peterson, testified that when Stacy was considering divorcing Peterson, she asked the attorney, "Can we get more money out of Drew if we threatened to tell police how he killed Kathy?," the Chicago Tribune reported Monday.
Shortly after that, in 2007, Stacy Peterson disappeared.
Smith's testimony was given during a hearing to decide which, if any, of a number of hearsay statements can be introduced as evidence in the upcoming murder trial of Drew Peterson, charged with Savio's 2004 death.
Savio's body was found in her bathtub and her death was ruled an accident. But after Stacy Peterson went missing, Savio's body was exhumed and her death reclassified as a homicide.
Prosecutors are expected to call their last witness in the now two-weeklong hearing this week.
Peterson's lawyers will then have the chance to call their own witnesses, the Tribune said.