Search warrant documents say a 46-year-old western Michigan man being investigated in the disappearance of a gas station clerk and accused in a jogger's slaying possessed a list of U.S. serial killers.

The documents released Tuesday also show pages of women's names and telephone numbers were among items seized from the Muskegon Township home of Jeffrey Willis. Documents also show police tracked him days before his May arrest.

Willis awaits trial in the 2014 death of 36-year-old Rebekah Bletsch and faces charges in the April kidnapping of a 16-year-old girl. Investigators say she escaped from Willis' van.

Authorities say Willis also is being investigated in the 2013 disappearance of then-25-year-old Jessica Heeringa from a gas station.

The Associated Press left a message late Tuesday for defense attorney David Kortering.