By Adam S. Levy,

Breaking Celebrity News Staff Writer

Lance Rogers and Matthew Pare, the attorneys for the woman who's filed a paternity suit against pop star Justin Bieber, told HLN Thursday night they're still sitting on "credible evidence" and undisclosed details that confirm the pop star is the baby's father.

As first reported by Star magazine, Mariah Yeater said in court papers filed in San Diego that she and Bieber had an unprotected, 30-second fling in a backstage bathroom at the Staples Center following an October 2010 show. She said the 30-second sexual encounter with the singer resulted in her son Tristyn Anthony Markhouse Yeater, who was born July 6.