I was surprised when I knew there was/is a Russian.

[nelson13]

I am living on campus, and my university is a collegiate one.

In the hall, I know a Russian, and which tense should I use to tell him?:

I was surprised when I knew there was/is a Russian.

[5jj]

You are more likely to use find out than know for this.

I was surprised when I found out there is/was a Russian here.

Both present and past tenses are possible.

[nelson13]

Thank you. When both present and past tenses are possible, does it mean the rules of reported speech apply here?