Trachtenberg's co-stars in "Gossip Girl" shared similar sentiments. Blake Lively, who played Serena van der Woodsen in the series, wrote in an Instagram story that Trachtenberg "w

The cause of death for actress Michelle Trachtenberg has been ruled “undetermined” by the New York City Medical Examiner, according to an agency spokesperson.

The cause and manner of Michelle Trachtenberg's death will remain undetermined, according to the New York City Office of the Chief Medical Examiner.