Officials with the Santa Monica Mountains National Recreation Area found the remains of the mountain lion known as P-55 on Wednesday.
P-55's monitor collar failed to emit a mortality signal and his body was too decomposed to determine a cause of death when it was discovered by officials, who mentioned rat poison or a fight with another male as possibilities.
The 3-year-old mountain lion's home range consisted of the northwestern end of the Santa Monica Mountains, generally west of Las Virgenes Road and mostly north of Mulholland Boulevard.
P-55 was photographed peering through the sliding glass door of a home in Westlake Village last February.