Chicago Area Local News

BOLINGBROOK, Ill. (CBS) ― Investigators want to know if anyone saw Drew Peterson's dark blue 2005 GMC Yukon Denali and Stacy Peterson's purple 2002 Pontiac Grand Prix on Sunday October 28, when Stacy Peterson was last seen alive -- or the next day, Monday, October 29.

The Illinois State Police want the public to help them in their search for a lead in the Peterson case and Stacy's stepsister, Kerry Simmons, is glad investigators are releasing the photos.

"Well maybe they found something in those cars that will be significant in finding evidence that something did happen with Stacy, Simmons said.

But Kerry Simmons wonders why it took so long.

"…to come out a month later I'm not sure that somebody is actually going to remember seeing those cars," she said.

It's clear the cars are central to the investigation. Sources say a cadaver dog may have hit on one of the vehicles. It's something that's been discussed on the Internet for weeks. But investigators won't confirm it.

Stacy's sister Cassandra Cales says Drew and both vehicles were gone when she stopped by Stacy's home at around 11 p.m. on the Sunday her sister disappeared. But when she drove back by the house a little more than three hours later she says Drew and the vehicles were back, but Stacy was nowhere to be found. Then the next day, neighbor Sharon Bychowski says Drew Peterson asked her to move Stacy's Grand Prix into her driveway next door.

"I said, 'I'm not really comfortable moving the car if that's going to be something they'd look at for evidence,'" Bychowski said. "He said wear gloves. That should be no problem."

The cars were confiscated by police days later. And while the cars are one focus of the investigation, bodies of water are another -- as detectives try to put together a body of evidence against Drew Peterson..

"It's been a big concern since day two or day three, since they first came in the home," said search organizer Roy Taylor. "There's been a lot of talk about water (when) we had Texas Equusearch here. They were very convinced she was in the water."

The FBI will join the search for Stacy Peterson, according to a Chicago-based spokesman for the federal agency. The FBI's involvement comes at the request of the Illinois State Police, who has reassigned investigators from around the state to assist with the case and has classified the investigation as a top priority.

Drew Peterson welcomes the FBI's help, since he said the organization often clears the name of those wrongly accused.

FBI spokesman Ross Rice said the agency has no reason to believe federal laws were broken, which would give it jurisdiction. But it has agreed to help, he said, just as it has with the ongoing investigation of another missing suburban woman: Lisa Stebic of Plainfield, who vanished April 30.

Charles Pelkie, a spokesman for the Will County state's attorney, said FBI investigators will be briefed by the state police on Monday. He said the FBI's involvement will add manpower to the investigation and provide technical assistance during water searches. It could even mean the U.S. Navy could get involved with their underwater equipment.

According to a press release from the Illinois State Police, daily searches continue by utilizing an airplane equipped with a heat-seeking device, canines, sonar devices, and the Will County Sheriff's Office rescue team. Investigators also continue to monitor Stacy's cellular telephone for any transmissions.

Anyone with information on the location and/or occupants of the vehicles is encouraged to contact the Stacy Peterson tip line at (815) 740-0678.

Family and friends will search for Peterson on Sunday, but a bigger search -- possibly the largest one yet, will take place next weekend. That search will involve search crews for Peterson and missing Plainfield mom, Lisa Stebic.

Peterson, 53, has not been called a suspect in Savio's death, but authorities have said they suspect him in Stacy Peterson's disappearance. He denies any wrongdoing and has proclaimed his innocence on the "Today" show, "Good Morning America" and in the pages of People magazine. 

The Associated Press contributed to this report.

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