Mountain lion P-22 was euthanized on Saturday after suffering from injuries and illnesses.
There was "no hope for a positive outcome" in letting P-22 live, wildlife officials announced.
The tests also showed the mountain lion suffered from multiple ailments, including kidney disease, a significant loss of weight, arthritis, and a parasitic skin infection all over his body.
P-22, who has been key to mountain lion research in the area, was likely born in the Santa Monica Mountains.
A trail camera picture of mountain lion P-22, in Los Angeles, California, U.S., 2012.