Updated 1.19pm: Police in Georgia have launched a criminal investigation into the circumstances surrounding events that led to the hospitalisation of the late Whitney Houston's daughter, Bobbi Kristina Brown.

She was found unconscious and lying face down in bathtub in Atlanta, apparently having suffered an overdose.

Her father, singer Bobby Brown, is reluctant to take the advice of doctors and remove her from life support.

The investigation is focused on Bobbi's boyfriend Nick Gordon.

There is a history of domestic violence involving the two.

Law enforcement sources say she has injuries that raised suspicions, possibly of an altercation over an hour before she was found in the bath in her home.

Her boyfriend and another friend found her in the bathtub.