Prosecutors reportedly believe the 25 year old arranged to get drugs for his 22-year-old girlfriend - who passed away on Sunday (26.07.15) - on the day she was found unconscious in her bath in January, TMZ reports.

Authorities are said to be trying to strike a deal with Max Lomas, who was in the house when the aspiring singer was discovered and is currently being prosecuted in Georgia for two drug-related felonies not related to the couple.

If he gives a frank and honest account of what happened, Max will be offered probation on the drug charges and immunity in Bobbi's case.

Prosecutors believe Nick had reason to know Bobbi Kristina had a drug problem and that she would indulge to the point of losing consciousness, but helped her obtain narcotics and then left her in harm's way.

According to the website, Nick claims he and Bobbi did drugs that morning, though sources stressed nothing was ''intravenously injected''.

An autopsy was carried out on Bobbi Kristina's body earlier this week but showed no obvious signs of foul play, while toxicology reports can only determine whether or not she was under the influence, leaving it unclear where any drugs would have came from.