The mysterious ailment that killed the National Zoo’s new baby panda last month will be revealed tomorrow, according to the zoo.

The six-day-old cub’s cause of death has so far been unclear to the public. A lack of outward physical trauma ruled out an accidental crushing death from panda mother Mei Xiang. While the female panda had extra fluid in its body and an abnormal liver, it’s not clear whether either of those factors led to its death.

The zoo plans to release the results of the panda necropsy and an update on Mei Xiang at 10 a.m. tomorrow.

The panda mother is apparently well enough to take media shots. At 9 a.m., she and panda father Tian Tian will be in their yards to receive “a frozen fruit treat.”

Flickr photo by the National Zoo used under a Creative Commons license