The King County medical examiner is looking for more information about three human skulls donated to a thrift store in the Seattle suburb of Bellevue.

The medical examiner said Wednesday in a statement that two are adult skulls that apparently were used in a medical clinic or for instruction.

The third is very old and appears to have belonged to a Native American child.

State law provides that the Native American skull must be returned to its tribe. The medical examiner is asking whoever donated the skulls to provide some details, without penalty, so that can happen.

The skulls were donated last month to the Goodwill store in Bellevue. Workers there realized they were human remains and contacted the medical examiner's office and law enforcement.