The Los Angeles District Attorney has not charged Chris Brown for the alleged assault on girlfriend Rihanna on Sunday morning in Los Angeles, but TMZ is reporting that the 19-year-old singer will almost certainly be charged with felony domestic battery in the case.

Citing unnamed "law enforcement" sources, the site reported early Thursday (February 12) that Rihanna told police that the alleged incident inside the couple's rented Lamborghini on the morning of the Grammys was not the first time Brown has attacked her. And though the evidence for the criminal-threats charge he was booked on Sunday night is described as "weak," the singer could face other charges once the D.A. takes the case, the site said.

The matter was kicked backed to police on Wednesday after the D.A.'s office cited insufficient evidence for the criminal threats charge, which is more serious than a domestic battery count. Numerous sources have said that the D.A. is reluctant to try such a high-profile case unless the evidence is very solid, which is why more evidence was requested. TMZ also claimed to have a more detailed rundown of event leading up to the alleged attack, which reportedly left Rihanna with a bruised and bloody face and bite marks on her arm and fingers. According to the police report cited by TMZ, after Brown allegedly received a text message from another woman, the couple got into an argument. TMZ reported that Rihanna would not initially tell police what set the fight off, but after the fight began, she "ordered him to drive her home and 'faked a call' to someone, saying things like, 'He's dropping me off. Make sure the cops are there.' "

The threat of police involvement reportedly enraged Brown, which is the basis of the criminal-threats charge. According to the report, Brown, 19, then allegedly began attacking Rihanna with his fists. During the fight, Rihanna reportedly took the keys out of the ignition and threw them outside the car.

TMZ claimed that the reports also include information that Rihanna told the police about an "ongoing and escalating abusive relationship" with Brown. Sources have also told MTV News that the relationship had hit a rough patch in recent weeks.

As both singers continue their silence in the wake of the incident, and the career fallout for Brown escalated to include sponsorship losses and radio stations dropping his songs, two unnamed friends also told US Weekly magazine that Brown may have roughed up Rihanna in the past. One unidentified friend said that Brown always had a "volatile" relationship with Rihanna and a confidant of the singer reportedly told the magazine that she had visible bruises on her neck in early December.

At the time, the friend reportedly asked, "is everything was OK with her and Chris," saying Rihanna explained, "'We broke up again.' I didn't pursue the issue further."

Brown's sister, Lytrell "Tootie" Bundy, told Extra on Wednesday that the singer is "doing good" and that, "he's coping ... He's doing ... [as well] as to be expected."She described her brother, who has been open about the alleged domestic abuse he and his sister witnessed in their home as children, as a "good boy — never violent."

Get resources and information about domestic violence, or check out Think MTV for a video handbook on spotting the warning signs of abuse.