Nick Gordon accused of injecting Bobbi Kristina Brown with " a toxic mixture ," according to new court doc allegations

A new accusation has surfaced in connection to Bobbi Kristina Brown's death, according to an ongoing $10 million wrongful death civil lawsuit filed against Brown's boyfriend, Nick Gordon. According to a new court document obtained by ET, Brown's conservator, Bedelia C. Hargrove, alleges that "Ms. Brown died due to a violent altercation with Defendant (Gordon) after which he placed her in a bathtub, unconscious, after he injected her with a toxic mixture." ➜ Watch: Could Nick Gordon be facing criminal charges in Bobbi Kristina Brown case? A previous amendment to the initial lawsuit had alleged that Gordon gave Brown a "toxic cocktail rendering her unconscious," though there was no reference to an alleged injection. Gordon has not been arrested in connection with Brown's death, and his lawyers previously called the initial "toxic cocktail" allegations "slanderous and meritless." The new documents surfaced shortly after the Fulton County District Attorney filed a motion to seal Brown's autopsy, allegedly due to fears of a potential flight risk f or defendants and possible harm to witnesses. "The criminal investigation involving possible charges in this case is ongoing, no arrests have been made, and disclosure of the autopsy report and the above mentioned information at this time would compromise the integrity of the investigation and create risk of flight of possible defendants, and could pose a danger to witnesses involved in this case," the filing read. A judge granted the motion on Sept. 28.