Illinois ? Authorities executed another search warrant late Tuesday in the case of a former suburban Chicago police sergeant suspected in his 23-year-old wife’s disappearance.

The latest warrant dealt with items inside two vehicles already seized from Drew Peterson’s home in Bolingbrook, said Charles Pelkie, a spokesman for the Will County state’s attorney’s office. He declined to elaborate.

Peterson’s attorney, Joel Brodsky, told WFLD-TV that the warrant says police are seeking items that “may have been utilized in commission of the offense of first-degree murder or the concealment of a homicidal death.”

The warrant also indicates interest in trace elements of several materials, including blue plastic, Brodsky told the Fox affiliate.

A relative of Peterson’s reportedly helped him move a heavy container out of his home and put it the family’s sport-utility vehicle the day his wife vanished, an allegation Brodsky denied last week. A nonprofit group helping to search for Stacy Peterson has said police asked them to look for a blue plastic barrel large enough to hide a body.