Police Chief Clifford Cook said investigators questioned Bethany Storro, confronting her with inconsistencies in her story, The Portland Oregonian reported.
"She is extremely upset. She is very remorseful," said Cmdr. Marla Schuman, describing Storro as being in a "fragile" emotional condition.
Storro, 28, who had recently moved to Vancouver, told police she was approached Aug. 30 by a young black woman who said "Hey, pretty girl, do you want to drink this," before throwing the acid in her face.
Police said the pattern of her injuries looked more as if the acid had been rubbed on Storro's face. She also said she had just purchased a pair of sunglasses that protected her eyes, but there were burns in areas that should have been covered by the glasses.
Schuman said prosecutors will decide whether to charge Storro.