Technically, neither state considers it suicide. I don't know if that rules out autopsy in practice though.

From the Oregon Death with Dignity Act:

Nothing in ORS 127.800 to 127.897 shall be construed to authorize a physician or any other person to end a patient's life by lethal injection, mercy killing or active euthanasia. Actions taken in accordance with ORS 127.800 to 127.897 shall not, for any purpose, constitute suicide, assisted suicide, mercy killing or homicide, under the law. [1995 c.3 s.3.14]

From Washington Initiative 1000:

Nothing in this chapter authorizes a physician or any other person to end a patient’ s life by lethal injection, mercy killing, or active euthanasia. Actions taken in accordance with this chapter do not, for any purpose, constitute suicide, assisted suicide, mercy killing, or homicide, under the law. State reports shall not refer to practice under this chapter as “suicide” or “assisted suicide.” Consistent with sections 1 (7), (11), and (12), 2(1), 4(1)(k), 6, 7, 9, 12 (1) and (2), 16 (1) and (2), 17, 19(1) (a) and (d), and 20(2) of this act, state reports shall refer to practice under this chapter as obtaining and self-administering life-ending medication.