Michael Dunahee vanished from a park near his Victoria home on March 24, 1991. (CBC)

U.S. police have found a "missing person" poster of a Victoria boy who disappeared almost 18 years ago at the Milwaukee home of a possible child killer, CBC News has learned.

Michael Dunahee disappeared on March 24, 1991, from a park near his home in Victoria. One of the biggest Canadian police investigations ever ensued, but he was never found.

At the time, his family believed Michael, then 4½ years old, had been abducted. His missing-person file remains open, and a Victoria police officer is still assigned to the cold case.

CBC News contacted Crystal Dunahee, Michael's mother, on Tuesday, but she declined to comment on this latest twist until after she receives more information.

According to Milwaukee police, Vernon Seitz, 62, confessed last month to his psychiatrist that he had killed one boy in 1959 and knew of another child killing. Milwaukee police later raided Seitz's home and found him dead of natural causes.

Child pornography uncovered

But officers made significant discoveries in his basement: piles of child pornography and files on unsolved missing children cases in the United States from the late 1980s and 1990s.

Milwaukee police are refusing to discuss the case, saying the investigation is ongoing, but CBC News obtained results of their search warrants Tuesday.

Among the hundreds of items seized in Seitz's basement were scores of drawings of nude boys in bondage, books on cannibalism, blond human hair and a bone.

A "missing person" poster of Michael was also found, along with a copy of a map of somewhere not in Milwaukee, titled "Millstream Park."

Northwest of Victoria, there is a Millstream Road that leads to several remote parks.

Victoria police said Tuesday they have not been contacted by any U.S. officers but are interested in any new leads or links in the Dunahee case.

While Seitz confessed to killing two children, he never mentioned anything involving the Canadian boy to his psychiatrist, Milwaukee police said.

Local investigators are attempting to trace Seitz's movements in the late 1980s and early '90s to determine whether he travelled to Canada, specifically B.C.