Pamela Ferrer was an average jewel thief who came across a meteor with a symbiotic alien snake inside. Soon as she came into contact with the creature, it merged with her, granting her such superhuman abilities as it corrupted her into killing her own partner for the jewels they've recently stolen.
Murdering Spree and Jewel Robbery
Pamela, having gotten used to the alien inside her, began killing more innocent people for their valuables, ripping their hearts out. Her actions also brought Supergirl and Martian Manhunter onto following up with the same case Alex and the DEO were following.
Soon as Brainiac 5 identified Pam's DNA match, he along with Supergirl, Alex and J'onn confronted Pamela in her penthouse. Soon as Brainic 5 ruthlessly kicked her without going good cop on her, Pam attacks the group and flees out the window.
After the authorities took all of the diamonds she stole, Menagerie grew furious and killed one of the Children of Liberty before going to the ball to steal whatever jewelry she can take.
After killing two people, the Children of Liberty engaged Menagerie. After fending off a few of the thugs, Supergirl takes the thief outside to subdue. After blowing Pamela into the local column of the building, Ben Lockwood's son decapitates the alien inside her, rending her harmless and leaving the authorities to arrest her as the Children of Liberty's success granted the government the approval on releasing Lockwood from prison.