It was Parallax's influence that was responsible for Jordan's subsequent murderous activity. When Jordan destroyed the Central Power Battery, he unknowingly freed Parallax, which grafted itself onto his soul, and suppressed Ganthet's memories of the parasite.
Parallax's influence led to Jordan's violent actions.  Jordan's destruction of the Central Power Battery inadvertently released Parallax, which attached itself to his soul and suppressed Ganthet's memories of the parasite.