Whatcom County Medical Examiner Gary Goldfogel said this week the cause of death for Hazel Christine Phair was alcohol poisoning.
The Whatcom Middle School student had returned from a party about 2 a.m. Sept. 29 and went to bed where she was found later that morning by her mother. Medics could not revive the girl.
A blood-alcohol level of 0.40 can be deadly even for adults. In Washington state, the legal limit for drivers is 0.08.
The Bellingham Herald reports toxicology tests showed Phair also had marijuana in her system. Police are still investigating her death.