Pierce County authorities are investigating whether hundreds of voter-registration cards were fraudulently filled out by paid canvassers...

Pierce County authorities are investigating whether hundreds of voter-registration cards were fraudulently filled out by paid canvassers before the 2006 election.

The criminal investigation, acknowledged Friday by Deputy Prosecuting Attorney Al Rose, comes on top of a continuing probe in King County. The King County investigation began after election workers in October spotted apparently forged voter-registration cards turned in by the community-organizing group ACORN, the Association of Community Organizations for Reform Now.

Rose said he expects to conclude the investigation in about a month. He declined to provide details about the possible fraud except to say it involves about 400 registration forms returned to election officials as undeliverable.

The new registrations have been flagged so the registrants won’t be allowed to vote unless they first prove their identity, Rose said.

Many, if not most, of the suspicious registrations used the address of the Tacoma Rescue Mission. Rick Shields, a shift manager at the shelter for homeless people, said a large amount of mail from the elections office arrived one day last fall addressed to newly registered voters.

“There were several that were in there that were legitimate” and were picked up by people who either stayed in the shelter or picked up mail there, Shields said. The rest of the mail was returned as undeliverable after 30 days.

Shields said it was clear when the mail arrived that some names weren’t legitimate. “They were like cartoon characters’ names and football players’ names. … We had a piece of mail coming for [Hall of Fame quarterback] Joe Montana. He lives in California; he don’t live here.”

Pierce County Auditor Pat McCarthy could not be reached for comment Friday.

In King County, election officials said in February that many of the 1,829 registration forms delivered by ACORN last October appeared to have been forged by a few people.

An ACORN attorney in March gave King County prosecutors the names of three temporary employees he said should be investigated for possible registration fraud. The attorney, Brian Mellor, said ACORN was considering filing civil lawsuits against the workers.

ACORN spokesman Kevin Whalen said Friday that Pierce County officials haven’t asked his organization for documents or information. “If they do ask, we’ll cooperate and help in any way we can, as we have in King County and with other folks in the past.”

Keith Ervin: 206-464-2105 or kervin@seattletimes.com