The female mountain lion known as P-39 was recently killed while trying to cross the 118 Freeway east of the Rocky Peak exit near Chatsworth, according to National Park Service biologists.

The death occurred on the evening of Dec. 3, but the incident was not reported to the National Park Service until a few days later, according to a news release from the National Park Service.

A biologist picked up the cougar’s electronic tracking collar on the freeway, but the big cat’s body has not been found.

• PHOTOS: Mountain lion P-39 killed, her kittens unlikely to survive

News of P-39’s death comes after a 10-day kill permit expired for another mountain lion P-45, suspected of killing a number of alpacas in the Malibu area.

P-39 is the mother of three 6-month-old kittens whose images have been captured on remote cameras set up by the National Park Service.

Santa Monica Mountains National Recreational Area biologist Jeff Sikich said in a statement that navigating the area’s complex network of roads is a major challenge for mountain lions.

The adult female’s three young kittens are not expected to live.

“Unfortunately it’s unlikely that the kittens have developed the hunting skills to survive without their mom,” Sikich explained.

• PHOTOS: The mountain lions of Los Angeles

This week, Sikich found P-39’s damaged GPS collar in the center divider of the freeway, according to the release, which suggests that the collar came off as a result of the impact with the vehicle.

Before Sikich’s discovery of the collar, National Park Service officials said, researchers suspected the mountain lion may have been killed because her collar stopped working and she was in the general area of the crash a few hours before it occurred.

But the remains of the mountain lion weren’t located, and witnesses who saw the animal did not report seeing a collar.

• RELATED STORY: P-45 cougar drama draws attention to proposed wildlife freeway crossing

Estimated to be 5 years old, according to park officials, P-39 was initially captured and outfitted with the GPS collar in April 2015. The female mountain lion is known to have had at least two litters of kittens, including the three youngsters known as P-50, P-51 and P-52.

P-39 had stayed in the wooded area north of the 118 Freeway since researchers started tracking her in 2015, according to park officials. But a few days before her death, the female had crossed the freeway successfully for the first time.

It is not clear if the kittens were traveling with their mother at the time of her death, according to the release.

P-39, who roamed the Santa Susana Mountains, was not as isolated as Malibu-dwelling P-45, the male cougar who outlasted his 10-day kill permit.

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P-39’s death is the 13th known case of a mountain lion killed on a freeway or road in the study region since 2002, according to the release.

An uncollared male mountain lion was killed near the 10-lane freeway in October 2008, officials said.

The area lacks adequate wildlife fencing to direct animals to a hiker/equestrian tunnel sometimes used as an undercrossing that is less than 1 mile away.

Meanwhile, during the 18 months that researchers tracked mountain lion P-3 in 2003 and 2004, he crossed the 118 Freeway 14 times successfully and used the tunnel multiple times, according to the National Park Service. But other animals have tried crossing the road itself with sometimes deadly consequences.