Who is Stepan Timoshenko from We the Living and what is their importance?

Stepan Timoshenko is the officer who captured Leo and Kira on their first morning aboard the ship. Timoshenko also makes the decision that Kira was kidnapped, and who tells Leo to keep her quiet. When Stepan discovers the note from Pavel to Karp indicating their relationship in the smuggling ring, he sends it to Andrei before committing suicide.