Complex sentence: A construction worker (Mitchell Kosterman) from his company, who has been doing his own EVP work, is holding Mary captive, he who has been under the control of the demons to kill all these people, including Anna.
Split into simpler sentences: A construction worker (Mitchell Kosterman) from his company, who has been doing his own EVP work, is holding Mary captive. He has been under the control of the demons to kill all these people, including Anna.