Atlanta (CNN) Investigators are focusing on Bobbi Kristina Brown's boyfriend, Nick Gordon, as they try to determine how she ended up facedown in a tub of water, a source with knowledge of the case told CNN.

In another development, a source close to her family told CNN that she has injuries that still need to be explained. The nature of those injuries was not disclosed.

Gill on Bobbi Kristina: 'Everybody is staying hopeful'

Gill on Bobbi Kristina: 'Everybody is staying hopeful' 02:23

Gill on Bobbi Kristina: 'Everybody is staying hopeful'

The daughter of musical superstar Whitney Houston, Bobbi Kristina was found facedown in a bathtub full of water in her Atlanta area home on January 31. The 21-year-old was "unresponsive, meaning not breathing, no heartbeat," a Roswell police spokeswoman said at the time.

Doctors have placed her in a medically induced coma, a source close to the family said soon after she was hospitalized. The status of her brain function won't be known until sedatives are reduced, the source said.

A week after she was rushed to the hospital, details of her condition are scarce. Sources close to the family say she opened her eyes briefly on Monday and also suffered seizures that same day. It was not immediately clear what medical significance these reported events have in Brown's case.

As she fights for her life, more family members are coming to Atlanta to visit the legendary singer's daughter.

Her grandmother, Cissy Houston, mother of the late Whitney Houston, arrived at Emory University Hospital on Friday, a source close the family told CNN.

Other family members, including Bobbi Kristina's father, singer Bobby Brown, have been in Atlanta for days.

She "was not breathing" when Gordon and a friend, who has been identified as Maxwell Lomas, found her inside her townhouse in the Atlanta suburb of Roswell.

They called 911 and performed CPR until emergency crews arrived and took over, police spokeswoman Lisa Holland said.

Nobody knows what caused her unresponsiveness, Holland said, but police consider it a medical incident at this time. She said investigators had found nothing to indicate it was drug- or alcohol-related.

Bobbi Kristina had said she was married to Gordon, but an attorney for her father said the two were never married.

Meanwhile, the three-year anniversary of Whitney Houston's death approaches.

She was found dead in a bathtub at a hotel near Los Angeles on February 11, 2012, hours before she was to attend a pre-Grammy Awards party.

A coroner ruled her death an accidental drowning , with heart disease and cocaine use listed as contributing factors.

Bobbi Kristina is her only child.