The key prosecution witness in the Sheldon Silver trial told a jury Wednesday that he panicked when investigators arrived at his Manhattan apartment in 2014 to question him about referrals he made to Weitz & Luxenberg in return for Silver sending state grants to fund his research at Columbia University.

Dr. Robert Taub, speaking from the witness stand in the second day of testimony at the kickback and extortion trial of the longtime New York state Assembly speaker, said investigators came to his door at 6 a.m. on a summer morning and asked him whether he had made valuable referrals to Weitz & Luxenberg, where Silver was of counsel.

Taub, who later agreed to cooperate with investigators, initially denied it.