Nick Gordon has been accused of giving Bobbi Kristina Brown a "toxic cocktail".
The 22-year-old aspiring actress', who passed away last month after six months in a coma, conservator has alleged Nick was responsible for the star suffering brain damage.
New court documents reportedly allege that Nick "gave Bobbi Kristina a toxic cocktail rendering her unconscious and then put her face down in a tub of cold water causing her to suffer brain damage."
It also claims that on the morning she was found unresponsive and face down in a bath tub, Nick had arrived home at six in the morning after "being out all-night on a cocaine and drinking binge." The pair are then said to have argued for around 30 minutes until "everything abruptly became quiet," NBC's 11 Alive reports.
In a statement, conservator Bedelia Hargrove said: "I am deeply saddened by the recent death of Bobbi Kristina Brown. I extend my sincerest condolences to all of her family.
"Consistent with and to the letter of the civil action I initially filed on behalf of Bobbi Kristina, we will continue to pursue justice for her. I have filed today an amended complaint against Nicholas Gordon adding a count for wrongful death and for pain and suffering. We will leave no stone unturned in seeking justice for Bobbi Kristina Brown."