Colonel in the Russian air force with 20 years of flight experience under his wing. He visited his friend, cosmonaut Anatole Konstantinov, who had just returned from a tour of duty aboard the International Space Station. There, at a Moscow hospital, the non-corporeal form of the Goa'uld Anubis transferred out of Konstantinov and into Vaselov's body.
Under Anubis's control, Vaselov had himself assigned to Stargate Command, where he petitioned General Jack O'Neill to admit him to any off-world unit (including the prestigious position as the new commander of SG-1). When Anubis realized O'Neill would not allow him through the gate the entity transferred out of Vaselov's body and into Dr. Daniel Jackson's.
Unfortunately, the damage had already been done. Anubis had been in his body long enough that Vaselov showed symptoms, not only of memory loss, but of skin lesions and a highly elevated white blood count.
Vaselov had a sister in Bryansk. When he realized his injuries were fatal he wrote a letter to her and asked Dr. Jackson to deliver it.
When he realized Anubis was about to be successful in escaping Stargate Command, Vaselov entered the Gate Room and shoved him down. A gun in his hand, Vaselov ensured Anubis, in the body of General O'Neill, would not leave the base unless he took the colonel's body. Anubis unwittingly agreed and reentered Vaselov, departing Earth through the active Stargate.
Lockdown - His body possessed by Anubis, Colonel Vaselov is reassigned to Stargate Command. But when he wakes up, he has no idea where he is or how he got there.