Deputy Travis Gullberg, Multnomah County Sheriff's Office spokesman, said the sculptures were taken late Wednesday or early Thursday, and a wheelbarrow that might have been used to take the art has been found.

The works are valued in the tens of thousands of dollars, but have little resale potential because of their large size. It's possible the pieces were turned into scrap or melted down, Gullberg said.

"In the past years, there's been a rise in metal theft," Gullberg said. "You get so much per pound for selling it. If that's the case, it may be that's what they (the thieves) were after."

Dorie Vollum said she didn't notice anything unusual leading up to the theft, though she says the property has been busy with construction work since Jean Vollum died in June. Jean Vollum was one of the city's most significant philanthropists of the past three decades and also an art patron who championed many leading artists.

Despite the rise in metal theft, there hasn't been a noticeable climb in art thievery, Gullberg said. He added that there were no leads in the case.

(Copyright 2007 by The Associated Press. All Rights Reserved.)