Police confirmed the remains as those of Karen Sterzl on Wednesday.
The Record of Stockton reports (http://bit.ly/11nEWS5) that the 36-year-old Sterzl was last seen on Dec. 22, 1990 at a houseboat she shared with her boyfriend in Stockton.
According to the Record, the boyfriend said Sterzl told him she and her mother were going to Montana to visit someone and planned to return on New Year's Day.
Officer Joe Silva says police uncovered the remains after receiving an anonymous tip about evidence related to Sterzle's case. They are now awaiting the official cause of death.
Silva says there is no obvious connection between Sterzl and the Manteca residence.