Nick Gordon fed Bobbi Kristina Brown a 'toxic cocktail' then placed her face-down in a tub of cold water on the last night she was seen conscious, according to a landmark lawsuit filed on Friday.

It adds a 'wrongful death' case against Gordon since he was accused of assault, battery, causing emotional distress, and stealing Brown's money in late June.

Brown, 22, was found unresponsive in a bath in January and remained in a coma for six months until her death on July 26.

Now, a week after her funeral, attorneys have filed an amended lawsuit, seen by NBC's 11 Alive, with astonishing new claims about the night Brown was hospitalized - including the news that there may have been another woman in the house with Brown, Gordon and their friend Max Lomas.

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New lawsuit: Nick Gordon fed Bobbi Kristina Brown a 'toxic cocktail' then placed her face-down in a tub of cold water on the last night she was seen conscious, according to a landmark lawsuit filed on Friday

Relationship: Police believe that Gordon knew that Bobbi-Kristina had a drugs problem but would still help her obtain them. He and Max Lomas found her unresponsive in her bathtub in January. She died on Monday

Connection: Gordon, pictured left, is now accused of 'wrongful death' after Bobbi Kristina (pictured right with her mom Whitney Houston) was found unresponsive in her bathtub in January. She died on July 26

NEW ALLEGATIONS The latest lawsuit contains a catalog of new allegations, including a detailed account of events on the night Bobbi Kristina was hospitalized. It is the first time prosecutors have claimed: - There was 'another woman in the house' - Nick Gordon 'watched video footage and listened to Bobbi Kristina's calls when he got home' - Gordon and Brown 'had a screaming fight that moved from the kitchen, into the living room, and up to the bathroom' - Gordon 'fed Brown a lethal cocktail then placed her face-down in the bath' then 'came out in different clothes and told a female guest he wanted a white girl like her' - Another friend 'found Brown 15 minutes later in the bath tub unresponsive with a tooth hanging out' Advertisement

The suit was filed by Brown's court-appointed conservator Bedelia Hargrove.

According to Hargrove, after police interviews with Max Lomas, Gordon had been 'out all-night on a cocaine and drinking binge.'

Once home, he watched camera footage of Brown and listened to her conversations, then accused her of cheating on him, the suit claims.

A screaming fight erupted between the pair, it is claimed, which moved from the kitchen, into the living room, then up to the master bedroom.

Eventually 'everything abruptly became quiet', the suit states, at which point Gordon '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.'

In an astonishing new revelation, there was supposedly a 'white girl' lying on the bed in the master bedroom as the alleged altercation played out.

According to the suit, Gordon came out of the bathroom wearing different clothes, lay his head on the ankle of a female guest, and said: 'Now I want a pretty little white girl like you.'

Fifteen minutes passed before another guest went into the bathroom to find Brown face-down and unconscious in the bath tub. There was a dust pan at the bottom of the tub, the suit states.

Gordon allegedly ran in shouting, 'Clean up! Clean up!'

The entire party then tried to resuscitate Brown, who had a swollen mouth and a tooth hanging loosely from her gums, the suit states.

Once Brown reached the hospital, and was placed in a medically-induced coma, she was diagnosed with 'global and irreversible brain damage...as a result of [Gordon's] actions,' the suit declares.

This is the first time police have given a detailed account of the night's events and revealed there was another woman in the property at the time.

Gordon was declared 'a person of interest' by police after Brown's death.

Prosecutors have reportedly spoken with Max Lomas, who was at Brown's Georgia home that day and is currently facing charges of two drug-related crimes. The charges are not connected with her death.

In exchange for revealing exactly what happened on the day of the incident, police would offer Lomas immunity in the criminal investigation into Bobbi Kristina's death and probation on the drugs charges, a source revealed to entertainment website TMZ.

It was reported that Lomas and Gordon found Bobbi Kristina face down in her bath in her home in January - though it now appears other guests were with them.

Gordon has previously said that the pair did drugs on the morning that she was found unresponsive in a bathtub.

But according to TMZ's source, police believe she had a serious problem with drugs - but he still helped her to obtain and use them.

Bobbi Kristina allegedly had a history of falling asleep in the bath after partying.

In February 2012, the night before her mother Whitney Houston died - after she was found unresponsive in a bath - Bobbi Kristina had been 'extremely drunk' after the pair had been partying together.

She drew a bath in her room at the Beverly Hilton Hotel, in Beverly Hills, LA, but had fallen asleep in the tub, waking up to find the room had flooded with water, law enforcement sources revealed to TMZ.

Tragic: Bobbi Kristina Brown had a history of falling asleep in the bath after partying, claim police sources

Devastated: Michelle Gordon, Nick Gordon's mother, said her son was traumatized by Bobbi Kristina's death. She said: 'Nick loved and cared for Krissi... he has suffered greatly each and every day they've been apart'

Michelle Gordon, Nick Gordon's mother, insists that the death of Bobbi Kristina has devastated her son and the rest of their family.

'Nick loved and cared for Krissi deeply, and he has suffered greatly each and every day they've been apart,' she said.

'Nick and our family are in mourning, and we ask that you respect our privacy.

'Our thoughts and prayers are with both the Houstons and the Browns during this difficult time.'

An autopsy of Bobbi Kristina's body shortly after her death found no obvious cause of death or significant injuries.

The Fulton County Medical Examiner issued a statement, saying additional laboratory testing will have to be conducted, which could take 'some weeks'.