LOS ANGELES, CA — A young mountain lion, a big boy from a 2015 litter of pups, has been found dead, and once again, rat poison is believed to be the culprit. National Park Service researchers tracking a big cat known as P-47 found his remains in the Santa Monica Mountains after the GPS collar the lion was wearing sent out a "mortality signal."

The three year-old lion had no visible wounds, but a necropsy showed he died a terrible death associated with the "anticoagulant compounds" found in rat poison, according to the Park Service. Liver tests determined he had been exposed to six anticoagulant compounds, and he suffered "internal hemorrhaging in his head and lungs." In recent years rat poisoning and freeway traffic have been among the leading causes of death for local mountain lions.

Although it's unclear exactly how the lion ingested the poison, researchers said lions often get it in their systems when they eat smaller poison-infected animals. According to the NPS, rat poisons have been found in 21 out of 22 local mountain lions they have tested.

"It's unfortunate to see an otherwise healthy mountain lion lost from what appears to be human causes," Seth Riley, wildlife ecologist for Santa Monica Mountains National Recreation Area, said in a statement. "In P-47's case, it's also a big loss because we don't believe he had yet mated and passed along his genes, which would have been valuable since he had ancestry from north of the Santa Monicas."

A reporter for the New Yorker tagged along with National Park Service researchers in 2017, when they captured and tagged P-47, describing him thusly: "Nose to tail, he was nearly seven feet long, covered in a thick mustardy coat flecked with black. His paws looked as big as a hand spread wide. Bottom heavy, his body tapered to an elegant head with a Greek nose. Under his neck the fur was rabbit-white and soft." RELATED: