Milana Li, a sixth-grade student at Conestoga Middle School, was found dead under "suspicious" circumstances just before 3 p.m. Tuesday when officers responded to the Westside Linear Park in Beaverton, Beaverton police have said.
Investigators said an autopsy performed Wednesday determined Li had been killed.
Li was last seen at her family’s apartment near the intersection of Southwest Murray Boulevard and Southwest Scholls Ferry Road around 4 p.m. Sunday.
Her mother reported her missing around 1:10 p.m. on Monday. Police initially described Li as a runaway.
Community members mourning Li’s death have left a memorial for the 13-year-old.
"My mother and I decided to plant some lavender and some purple flowers by the creek," Li’s classmate Savanna told KOIN-TV. "We wanted something that will just stay there for her."
Investigators have released no further details on the investigation or on how Li died.
Police don’t believe there is a continued threat to the community but stressed that this is an ongoing investigation.
Beaverton is located about seven miles west of Portland.