Doug Rasmussen was a corrupt SEC investigator who was looking into Adam Saunders' trading at Baylor Zimm. Disgusted that the government has defanged the SEC, Rasmussen set out to use his position to make a profit. He and Paul Ashton were responsible for the short sale and collapse of Tritak Energy. After a team of assassins failed to kill Adam, Adam and Finch were able to undo the damage Doug and Paul caused. Adam revealed to them that all the stock brokers they used were ready to testify against them and Doug tried to flee as the police arrived. However, he was clothes-lined by Reese and arrested.
Rasmussen was actually working for Elias who needed the money to finance a personal war. He was "arrested" by Scarface, taken to his apartment in Queens and murdered in such a way that it looked like a suicide to cover up Elias' involvement in the plot.