Investigators are now focusing on the GPS system in Drew Peterson’s car as they search for his missing fourth wife, Stacy Peterson. According to search warrants obtained Wednesday by the Chicago Tribune, police are examing the records from the OnStar system in Drew’s SUV. However, a spokesman for OnStar says the global positioning system does not constantly monitor a vehicle’s location. “The only time we would know where the vehicle is, is when the driver initiates contact to OnStar or when the vehicle has been in an accident, the air bag deploys and the vehicle automatically calls us for help,” OnStar’s Jim Kobus said.

The latest search warrant in the case also called for the seizure items containing plastic shavings, blood, bodily fluids, fingernail scrapings, chemicals that may alter the decomposition of a body and “biological material that may be evidence of the offense of first-degree murder,” according to the Tribune.

Stacy Peterson disappeared Oct. 28, leaving behind four children and many grieving family members. Despite her husband Drew’s assertion that Stacy ran off with another man, everyone close to Stacy says she would never leave her children, and Illinois police have declared her husband a suspect in what appears to be a homicide investigation.

Pick up the new issue of The ENQUIRER for more in-depth details on Stacy’s final minutes of terror.