Dean G. Skelos, the former majority leader of the New York Senate, and his son were found guilty of federal corruption charges on Friday, a quick and devastating follow-up punch to the State Capitol, which has seen two entrenched leaders convicted and removed from office in less than two weeks.

The jury in Federal District Court in Manhattan took roughly eight hours over two days to reach its verdict against Senator Skelos, 67, and his son, Adam B. Skelos, 33, finding them guilty of all eight bribery, extortion and conspiracy counts.

The Skeloses were undone by the perversion of a simple fatherly impulse: There was little that the elder Skelos would not do, or ask, for his son. They used the father’s position as majority leader to pressure a Manhattan developer, an environmental technology company and a medical malpractice insurer to provide Adam Skelos with roughly $300,000 via consulting work, a no-show job and a direct payment of $20,000.

Dean Skelos, a Republican from Long Island, had been one of the most powerful men in state government until his arrest this year, and his conviction — along with the conviction of his former colleague, the longtime Assembly speaker, Sheldon Silver, a Manhattan Democrat — is sure to have repercussions beyond the courtroom. As in Mr. Silver’s case, which ended on Nov. 30, the verdict resulted in Mr. Skelos’s expulsion from the State Legislature, where both men had served for more than three decades.