Bobbi Kristina Brown's organs are reportedly starting to shut down as her overall condition continues to deteriorate.

According to TMZ's "reliable family sources," after briefly showing improved brain function, the only daughter born to Whitney Houston and Bobby Brown remains comatose and on life support. The 21-year-old Brown has not regained consciousness since being found face down in a tub of water in the Roswell home she shared with boyfriend Nick Gordon more than two weeks ago.

Doctors immediately placed Bobbi Kristina in a medically induced coma, and since then she has shown little signs of improvement as doctors have advised family members to prepare for the worse.

Through it all, Bobby Brown continues to cling to his strong religious beliefs and has vowed not to remove his daughter from her ventilator, according to TMZ.

Meanwhile, police reportedly have launched a criminal investigation into the incident with Gordon, who is now believed to be a primary target. Sources say a number of unexplained bruises and injuries to Brown's body led police to begin their probe. WSB-TV in Atlanta also reports Brown had injuries to her face and mouth.

Reports have also surfaced that investigators are looking into what they believe to be drugs that were found in the home.

No charges have been filed in connection with the case, though family members reportedly have banned Gordon from visiting his girlfriend.

The Brown family recently gathered to hold a public prayer vigil for Brown that was attended by family church members, local community leaders and concerned supporters.

"Tonight meant a lot to see the family, to see supporters come out in prayer for my cousin, it means a lot to the family," said Shayne Brown.

Bobbi Kristina Brown's tragedy came almost exactly three years after her mother's lifeless body was found in the bath tub of her Beverly Hills hotel room. Authorities have since ruled Whitney Houston had drugs in her system at the time of her death.