AceShowbiz - More than 10 years after Brittany Murphy's mysterious death, an upcoming documentary is billed to shed more light on her final days and her relationship with her husband Simon Monjack, who died just five months after her from similar causes. On "What Happened, Brittany Murphy?", director Cynthia Hill unearths the British screenwriter's alleged shady past.

Speaking to PEOPLE in a new interview prior to the documentary release, Cynthia calls Simon "disturbed" and accuses the late screenwriter of "conning" the actress prior to her death. "He was a disturbed individual who was used to conning people and Brittany was one of his last victims," the helmer says of Simon. "There was a pattern of behavior that became very obvious the more research that we did."

Simon's ex-fiancee Elizabeth Ragsdale also accused him of lying to her about who he was. On the docuseries, it's recounted that Simon and Elizabeth got engaged after brief courtship. Shortly after, she became pregnant and Simon insisted she give birth in the U.S.

Elizabeth says she moved to the U.S. when she was four months pregnant and Simon paid for her plane ticket to New York, but after she got there, he allegedly abandoned him. "When I got to my little studio in New York, I called him and he answered. I said, 'Simon, I've made it to ...' and before I could get that sentence out, he hung up on me. He left me pregnant and abandoned," Elizabeth says in the doc.

Makeup artist Trista Jordan, who appears in the documentary and worked with Brittany in her last film, 2009's "Something Wicked", goes on recalling her final days. "Her eyes were so sunken, and she just seemed so sad," Trista remembers. "She wasn't herself. She was in so much pain. She had Bambi legs and couldn't stand up."

Brittany died on December 20, 2009 after she was found collapsing in a bathroom. L.A. County Coroner Asst. Chief Ed Winter concluded in February 2010 that the "Clueless" star's death was the result of untreated pneumonia, combined with anemia and drug intoxication from prescription and over-the-counter medications, including painkillers and cold medicine.

The documentary also includes interviews with Simon's mother Linda and brother James. It will air on HBO Max on October 14.