Dmitry Zaikin

Zayikin was assigned as backup commander for Voskhod 2. He then went on to graduate from the Zhukovsky Military Engineering Academy of Monino in 1968.[2] He left the space service on 25 October 1969 for medical reasons while training for Soyuz missions.[3] He then became an instructor and lead engineer at the Yuri Gagarin Cosmonauts Training Center.

For details: https://en.wikipedia.org/wiki/Dmitry_Zaikin