Lavro Kessar was a high-ranking officer of K-Directorate. Upon the assassination of Ilych Ivankov by Sark, he became the new leader.
Season 1
Ilych Ivankov and Lavro Kessar, as well as a bodyguard for each men met with Sark in Moscow discussing the terms of a Rambaldi artifact. After Ivankov said he wouldn't sell the artifact, despite being offered $100 million, one of Sark's bodyguard shot and killed Ivankov and his guard. Lavro and his guard quickly put their hands up in protest, not wanting to be killed. Sark told Lavro that he was now the new leader of the group and that he had 30 seconds left to agree, which he did (The Coup).
After Ivankov's murder, Lavro went missing and was presumed captured by Sark and "The Man." However, Lavro showed up looking perfectly fine a few days later and appeared to be working with Sark. The two men traveled to Tunisia to collect the Rambaldi manuscript, but neither of them received it. Sydney had subdued all the K-Directorate agents on the yacht the exchange was supposed to take place and stole the boat, along with the manuscript (Page 47).