Police: Chris Brown Beat, Choked, Threatened to Kill Rihanna; Text Message May Have Triggered Rage

The Los Angeles district attorney has reportedly asked police detectives to dig up more evidence as they build their case against singer Chris Brown.

The police are getting cooperation from Rihanna, Brown's alleged battery victim, and what she has told them so far is even more chilling than presumed.

E! News reports that Rihanna has alleged to police that Chris Brown not only inflicted horrific injuries on her, but choked her while threatening to kill her.

She says she lost consciousness in the midst of this.

The couple is said to have been squabbling after leaving Clive Davis' pre-Grammy Awards party late Saturday. Shortly after midnight, things blew up.

Cops say a message from a woman who wrote about hooking up with Brown may have played a role in triggering the argument. However, there's also a reference in the police report to an argument over a rapper, but this is NOT the woman who texted Brown.

In any case, Chris Brown pulled his rented Lamborghini to the side of a street in L.A.'s Hancock Park area. That was when Rihanna allegedly grabbed the car keys and tossed them out the window, sending Brown into a blinding rage.

Rihanna's account of her assault by Chris Brown is disturbing to say the least.

He tried in vain to find the keys, then came back to the car, put his hands around her neck and, according to the insider, said, "I'm going to kill you!"

According to the source, the 20-year-old "Disturbia" singer told L.A. police investigators that she lost consciousness, and when she awoke, Brown had fled.

Rihanna's right eye was blackened and badly swollen, and she had hand prints on her arms after she regained consciousness.

The responding officers were so concerned about her, they drove Rihanna to the hospital in their squad car instead of waiting for an ambulance.

Officers took two sets of photos of the banged-up star, one at the scene and the second after she was admitted to Cedars-Sinai Medical Center for treatment.

According to a source cited by TMZ, Brown allegedly hit Rihanna so hard, she could barely open her eyes - they were almost completely swollen shut.

She had a fat lip, her mouth was swollen, her nose was badly bloodied, and she had contusions on her forehead and on both sides of her face.

Those photos were presumably among the evidence presented to the D.A.

After being treated for her injuries, police escorted Rihanna down a rear elevator and into a waiting Mercedes, the source close to the case says.

Chris Brown, 19, was subsequently arrested for battery and on suspicion of making criminal threats. He was released after posting $50,000 bail.

His lawyer, Mark Geragos, has not responded to repeated requests for comment on the allegations. Brown's publicist also has not commented on this.

A spokeswoman for Rihanna declined to comment specifically on details of the fight and the arrest and stuck to her earlier statement from Sunday:

"Rihanna is well. Thank you for concern and support."

If the incident with the car keys was what led Brown to completely fly off the handle, there is no confirmed account of what the couple was fighting about.

A number of rumors have surfaced, such as the text message theory above or that Rihanna gave him herpes, but nothing conclusive or detailed.