ATLANTA (AP) — Authorities say an autopsy will be needed to evaluate what led to the death of Bobbi Kristina Brown, daughter of singer Whitney Houston.

In a statement Monday morning, the Fulton County Medical Examiner's Office says the time that elapsed from when she was found unresponsive until her death Sunday will "complicate" its effort to reconstruct what happened.

Bobbi Kristina died Sunday at Peachtree Christian Hospice in Duluth, Georgia, about six months after she was found Jan. 31, face-down and unresponsive in a bathtub in her suburban Atlanta townhome. She was 22.

A police report described it as a drowning.

The medical examiner says interpreting autopsy findings will also be challenging, but said it could be helpful to address questions about what caused her to become unresponsive.

Bobbi Kristina was the only child of Houston and singer Bobby Brown.