ATLANTA: An initial autopsy on Bobbi Kristina Brown on July 27 found no significant injuries and no obvious underlying cause of death for the daughter of the late singer Whitney Houston, who died on July 26 after sustaining irreversible brain damage in January.

The Fulton County Medical Examiner’s office in Georgia said Brown, 22, had no previously unknown medical conditions that would have contributed to her death.

It also said it has issued subpoenas to help gather documentary information on her death, and would conduct additional tests that are expected to take several weeks.

Brown, the only child of Houston and R&B singer Bobby Brown, died at an Atlanta-area hospice where her family had placed her a month ago after giving up hope she would recover. She died six months after an unexplained incident that left her unresponsive in a bathtub in her suburban Atlanta home.

“Krissy was and is an angel. I am completely numb at this time,” Bobby Brown, in his first comments on his daughter’s death, said in a statement issued by his lawyer.

“My family must find a way to live with her in spirit and honour her memory. Our loss is unimaginable. We thank everyone for the prayers for Krissy and our family as we mourn my baby girl,” he added.

The Medical Examiner’s office had said earlier that efforts to determine what happened to Brown in January would be “challenging” given the time gap between the bathtub incident and her death. She was found face down in the bathtub by her boyfriend, Nick Gordon, and a friend on January 31.