Rihanna photographed in Mexico

Singer Rihanna arrives at the 2008 American Music Awards in Los Angeles November 23, 2008. [Agencies]

Beaten-up beauty Rihanna donned a bikini and soaked up some Mexican sun at a private villa on Saturday, a day after her 21st birthday.

Photos of her south-of-the-border sojourn ran in today's print edition of the New York Daily News and quickly turned up online. The shocking bruises that sources say boyfriend Chris Brown left on the songbird's face just before the Grammy Awards were not visible in exclusive photographs obtained by the Daily News.

Nor was she smiling.

Her grim expression, so at odds with the balmy setting, hinted at the heartbreak the "Umbrella" singer has endured since her private agony became public knowledge.

Rihanna's family was furious after a photograph of her battered face was leaked, and the singer was determined to get out of Los Angeles.

On February 25, the L.A. district attorney's office said the investigation was still open and no decision on charges has been made.

Shortly before she split last Thursday, Rihanna released a note to her fans telling them "she remains strong."

Then, with a couple of close friends, Rihanna decamped for a private beachside villa in Punta Mita.

Brown, a 19-year-old R&B singer, was arrested on suspicion of making criminal threats against Rihanna after the Feb. 8 attack. He has since enrolled in anger management classes.