Brown, 19, was arrested Feb. 8 after an alleged physical altercation with his 21-year-old girlfriend, recording artist Rihanna, in a car in Los Angeles.
He was released on bail and due to be arraigned next week but that court appearance "may not happen," Los Angeles district attorney spokeswoman Jane Robison told E! News.
"We don't have the evidence yet. (Los Angeles police detectives) are still investigating," Robison said. "If (detectives) determine they need more time, they'll set a new date for him to come into court."
Meanwhile, the New York Daily News reported Thursday that photographs taken of Rihanna in Mexico last weekend showed her face apparently clear of the bruises she sustained in her alleged confrontation with Brown. The Daily News said the pictures it has obtained also showed Rihanna unsmiling and wearing a bikini.