A high-profile Chicago attorney, on the legal team of the 20-year-old California woman who's claiming Justin Bieber is the father of her 3-month-old son, told the Dr. Drew show on Tuesday that her lawyers attempted to contact Bieber's lawyers before the case was filed, and never received a response.

Yeater’s team hoped to settle the case “outside of court,” said Jeffery Leving, a lawyer known for his work as an activist for father's rights in divorce and custody cases.

Leving added he wants a “carefully supervised” DNA test to establish paternity.

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A top lawyer who once advised the White House on paternity law has joined the legal team of the woman who claims she became pregnant after a brief sexual encounter with 17-year-old singing sensation Justin Bieber last October, RadarOnline.com has exclusively learned.

In a statement, released to RadarOnline.com, the law offices of Lance Rogers said: “We are proud to announce that attorney Jeffery Leving is joining Mariah Yeater’s legal team. Jeffery Leving is a noted Fathers’ Rights attorney and he is the President of the Illinois Council on Responsible Fatherhood (see dadsrights.com).

He is a national expert on family law issues. Mr. Leving has been named one of “America’s Best Lawyers” by Forbes Radio and selected by his peers as one of Illinois’ top attorneys.  He co-authored the Illinois Virtual Visitation, Right to DNA Testing Notice and Joint Custody laws. He received the President of the United States Service Award, the nation’s highest honor for volunteer service directed at solving critical social problems.”

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.

“In the relevant time period, she wasn't having sex with anyone else,” Pare said. “That's how we know Justin Bieber is, in fact, the father of the baby... we need the paternity test to verify that scientifically, 100-percent.”