After tromping through Hammel Woods for five days looking for missing mom Stacy Peterson, the FBI and Illinois State Police have called it quits.

The massive FBI mobile command center set up in a parking lot off a Black Road entrance to Hammel Woods was gone by Friday afternoon and there was no sign of federal agents or state troopers lurking around the Shorewood forest preserve.

District 5 state police spokeswoman DeAnn Falat failed to return calls Friday about the aborted search effort. Coroner Patrick O'Neil confirmed no remains were discovered during the week-long operation.

The search attracted a great deal of attention, as a couple dozen agents and troopers showed up, put a boat in the water and poked around the park with dogs Monday. But that didn't stop the state police from trying to keep a low profile, as they lied to Will County Forest Preserve officials and told them they were merely conducting a practice exercise, two sources said.

The state police later admitted they made that up and were actually in the woods to look for Stacy Peterson, a source said.

FBI spokeswoman Joan Hyde confirmed earlier this week that agents were in Hammel Woods "working with ISP as part of an ongoing criminal investigation."

That investigation, a highly placed state police source said, involves figuring out what happened to Stacy Peterson, who vanished in October 2007.

Soon after Stacy mysteriously disappeared, state police Capt. Carl Dobrich declared that she was the victim of a "potential homicide" and named her husband, Bolingbrook police Sgt. Drew Peterson, the sole suspect in the criminal investigation.

The state police have yet to charge Peterson with harming Stacy, who is his fourth wife, but they did arrest him in May 2009 for allegedly killing his third wife, Kathleen Savio.

Savio was found drowned in a dry bathtub in March 2004. The state police quickly determined her death was the result of a freak bathtub accident and closed the book on her case. But when Stacy vanished three and a half years later, the state police were forced to re-evaluate that decision.

Peterson was found guilty of Savio's murder in September. He faces up to 60 years in prison when he is sentenced on Jan. 10.

A state police source said this week's search was not prompted by new clues or information, but was just one of numerous periodic operations carried out in what are believed to be promising locations.