Ross Vetter was a Captain in the Navy who worked at the Department of Acquisitions located in the Pentagon, making Jessica Smith his C.O. At some point, Vetter began accepting kickbacks in exchange for government contracts, drawing the interest of the FBI who started an investigation against him.
Vetter was placed on admin leave pondering the outcome of the case. During that time, he took to staying at home and began drinking rather heavily. When Smith stated that there was a possible crime that took place in her home, NCIS were called in and began their own investigations.
They eventually discovered the FBI's open case file regarding Vetter and Special Agent Leroy Jethro Gibbs learnt from FBI Agent Tobias Fornell that NCIS had been shut out off the case as the FBI had resorted to very unusual techniques to get Smith to co-operate such as wearing a wire while at work. A further investigation revealed Smith who had been since murdered with her death disguised to look like a suicide had been sleeping with Vetter as well. Gibbs and Fornell conducted a joint interview and were able to finally arrest the ones responsible for Smith's death.
Although Vetter's final fate is not known, it's presumed that his wife divorced him after learning of his affair with Petty Officer Smith and that he was discharged from the Navy in disgrace and eventually imprisoned after being found guilty of illegally accepting kickbacks.