Experiment 461 was the 461st genetic experiment created by Jumba with Hämsterviel's funding. She was designed to win race.
461 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.
All of the experiment pods were released and scattered across the island of Kauai.
At the unknown point, she was activated, captured, tamed and named Pacer.