The FBI is investigating whether Phylicia Barnes, the star student from North Carolina whose nude body was found in April, nearly four months after she went missing in Maryland, was a victim of sexual exploitation or child pornographers before her murder.

Federal investigators are seeking warrants to gain access to Facebook and email accounts belonging to Barnes, 16, and to four men from Baltimore, according to a report from ABC News affiliate WSOC-TV in Charlotte, N.C.

According to the Charlotte Observer, FBI Special Agent Jacqueline Dougher wrote in the request for the warrants that investigators have "reason to believe" the search will uncover evidence of child sex crimes or child pornography.

An autopsy conducted by the Office of the Chief Medical Examiner in Maryland determined her death to be a homicide, the state police said in May.

At the time, police said they knew the cause of death, but were not releasing the information because it is an ongoing investigation.

"To release a cause of death at this time could jeopardize the investigation by revealing information known only to the person or persons responsible for her death," Maryland State Police said in a statement in May. "The cause of death will be made public at an appropriate time in the future."

They have still not announced the cause of death and if police have identified a suspect, they have not told the public.

"If they get some suspects, they want to be able to talk to them about this, and say it hasn't been covered by the media so only they would know the details," Maryland State Police spokesman Greg Shipley told ABC News in May.

Barnes went missing in the Baltimore area while visiting her sister from Monroe, N.C., in late December.

She was last heard from Dec. 28 via Facebook when she posted a note saying she was at her sister's apartment with her sister's boyfriend.

The 5 foot 8 inch straight-A, African-American student was listed missing until her naked body was discovered in the Susquehanna River, nearly 35 miles from Baltimore, in late April.

The body of Darryl Harper, 53 of Richmond, Va., was discovered in the same river several hours after the discovery of Barnes' body. Police have said there is no connection between the two.