San Bernardino police are investigating complaints star singer Chris Brown may have been the victim of identity theft while he was an inmate at the country jail there.

According to TMZ, back in April when Brown was taken into custody by California police for leaving rehab without a judge's permission, one of the stops authorities made while transporting him to Washington, D.C. to face the judge was the San Bernardino institution.

The website adds that, though Brown was only housed there for three days, part of his stay required him surrendering a jail ID, which reportedly was left at the facility with staffers even after Brown was further extradited out East.

This week, Brown's attorney Mark Geragos went public with allegations someone has since tried to sell the ID online for at least $10,000. Reports are investigators have presently traced the attempted sale of the card to a West Coast man who claims he got it from a friend who received it from a friend.

TMZ adds police are still investigating and are desperately trying to decipher how the ID may have gotten out of the possession of jail staffers first entrusted to safeguard it.

Meanwhile, Brown doesn't seem to be stressing too much over any of it. HollywoodLife.com reports he and on-again, off-again model girlfriend Karrueche Tran recently "spent a wildly romantic night out together in Los Angeles... toasting something with Cristal."

Despite the fact the 25-year-old Brown could face jail-time at an upcoming March court hearing stemming from an alleged violation of his probation, reports are that the couple have been getting closer in recent weeks.

"They were definitely celebrating something," an eyewitness told HollywoodLife.com. "They were smiling, laughing a lot. And they sat side by side, rather than across from each other. Chris said he wanted to be as close as he could to his lady."