NEW YORK (CBSNewYork) — A key witness for the prosecution took the stand in the corruption trial of former Assembly Speaker Sheldon Silver.

Silver said nothing as he arrived at U.S. District Court in Lower Manhattan for his corruption trial on Wednesday, CBS2’s Dick Brennan reported. The prosecution’s star witness would do all the talking on the stand.

Dr. Robert Taub said he referred cases to Silver’s law firm in order to get research funding.

Taub testified that when he was initially approached by investigators he lied and denied the referrals saying, “I was terrified and I panicked and I wanted to divorce myself from any pending investigation.”

Taub later admitted that he referred over 25 clients to Silver, hoping the powerful assembly leader would fund his research center.

“I hoped to develop a relationship with him that would help fund mesothelioma research and would help my patients,” he testified.

He said that Silver, “conveyed that he was pleased with the referrals he was getting.”

Silver is charged with earning $5-million by selling his office in exchange for bribes and kickbacks.

Prosecutors said in the referral scheme, Taub referred clients to Silver’s Weitz and Luxenberg firm.

The head of the firm testified that Silver never told them the referrals came from a doctor who got state grants.

“There wasn’t any discussion about that,” Perry Weitz said.

Silver’s lawyers argued that he was making a legitimate income outside his assembly salary , and that prosecutors are trying to make that a crime, when it is not.

Dr. Taub also testified that Sheldon Silver helped his children get jobs.