Michelle Trachtenberg decided to "pull back from Hollywood" after her career as a child and teen star, a source exclusively tells PEOPLE, adding that leading up to Trachtenberg's unexpected death, she was more of a "recluse" but "always kind,

Multiple reports say the 39-year-old ‘Gossip Girl’ star had a liver transplant in the past year, but without an autopsy her death certificate will say her cause of death is