Kan. Stat. § 65-2893
In any case of death wherein notification of the coroner is not required by K.S.A. 22a-231, and amendments thereto, or any case in which the coroner does not elect to perform an autopsy, an autopsy may be performed upon the body of a deceased person by a physician or surgeon when so authorized, in writing by the decedent during his lifetime. Additionally, unless the physician or surgeon has knowledge that contrary directions have been given by the decedent, the following persons in the order of priority stated, may consent to the performance of an autopsy:
If there is no surviving spouse and an adult child is not immediately available at the time of death, the autopsy may be authorized by either parent; if a parent is not immediately available, it may be authorized by any adult brother or sister. Such autopsy shall not be performed under a consent given as required by a member of the class listed in subsection (b), (c) or (d), if, before such autopsy is performed, any member of the class shall object to the performance of such autopsy in writing to the physician or surgeon by whom the autopsy is to be performed.
K.S.A. 65-2893