An initial post-mortem examination of Bobbi Kristina Brown has found no significant injuries and no obvious underlying cause of death, a medical examiner said.
Bobbi Kristina Brown died on Sunday after spending months in a medically induced coma.
The 22-year-old was found unresponsive in a bathtub in her Atlanta home on 31 January.
In a statement on Monday morning, the Fulton County Medical Examiner’s Office said the time that elapsed from when Ms Brown was found unresponsive until her death would “complicate” its effort to reconstruct events.
The incident was described as a “drowning” by police, and doctors said Brown had suffered irreversible brain damage.
R&B singer Bobby Brown described his daughter as “an angel”.
“I am completely numb at this time,” he said in a statement.
“My family must find a way to live with her in spirit and honour her memory. Our loss is unimaginable.”
A $10m civil lawsuit filed last month accused Ms Brown’s partner Nick Gordon of causing her life-threatening injuries and stealing from her bank account while she was in a coma.
“The Roswell Police Department continues its investigation into the circumstances preceding and surrounding the time of the original incident leading to her death,” the medical examiner said.
No charges have been filed in the case.
Brown was found face down in the bathtub at the home she shared with Gordon, who was her adopted brother.