The female California mountain lion biologists named P-39 is suspected to have been hit by a car.
The female California mountain lion is believed to have been hit by an automobile on Dec. 3 while crossing the 118 Freeway near Chatsworth. The 5-year-old mountain lion was likely traveling just east of the Rocky Peak exit near Santa Susana Pass State Park.
The remains of P-39 still remain missing except for her tracking collar researchers placed on her in 2015.
Pictures of her kittens P-50, P-51 and P-52 quickly traveled far and wide when researchers found them in June 22, 2016.
The kittens were found to be only 4-weeks-old at the time of discovery.
"Unfortunately, it's unlikely that the kittens have developed the hunting skills to survive without their mom," biologist Jeff Sikich said in a statement.
Park service did not discover that P-39 had been hit by a vehicle until a few days later.
According to park service officials, "Researchers suspected P-39 may have been the victim because her GPS collar stopped functioning and she was in the vicinity just a few hours before the collision, but the remains of the animal were never found located and witnesses who saw the animal did not report seeing a collar."
Sikich, who works with the Santa Monica Mountains National Recreation Area searched for the collar and found it in the freeway's center divider.
It appears the collar flew off when P-39 was struck.
P-39 is the 13th mountain lion to be killed attempting to cross a Los Angeles County road since researchers began tracking them in 2002.
California Department of Transportation proposed building a landscape over the freeway to give wildlife a safer opportunity to cross.