Valerie Irwin found the Smilodon when he was a cub in her garage and decided to raise and tame him, believing he was an escaped government genetic experiment. At an unknown point, the Smilodon killed Valerie's boyfriend Dave, forcing her to bury his body in the park's forest.
After the Smilodon caused deaths, the Anomaly Research Centre team comes to investigate and Valerie believes that it's a government organisation that had created the Smilodon in a genetic experiment and now wanted to recapture and experiment on him, although she sympathizes with Stephen Hart. She distracts the team several times in order to protect her Smilodon.
When Nick Cutter goes to Valerie's house and discovers that she harbors the Smilodon, Valerie traps him and threatens him with a tranquiliser gun, then she sets the Smilodon on him. He manages to escape the house and tries to defend himself with a pitchfork, but Valerie arrives and tries to calm down the Smilodon, but, in his frenzy, he attacks and kills her.