True crime author Arthur Jay Harris said he has uncovered witnesses who told police they saw Dahmer at a mall in Hollywood, Fla., north of Miami, the day 6-year-old Adam Walsh was abducted.
Only the boy's severed head was later found in a drainage canal, and the case remains open. The boy's father, John Walsh, went on to create the "America's Most Wanted" TV show.
Harris has support from retired FBI agent Neil Purtell, who worked on the Dahmer case, which eventually resulted in 15 life convictions for murder.
"It smelled. All the right smells were there. That's the way I looked at it," Purtell told WISN-TV, Milwaukee.
Dahmer was beaten to death by another inmate in a Wisconsin prison in November 1994.