Looking for origin of surname?

[littleladyxx]

Hi, I've recently become interested in my fathers side of the family. The surname is Teresko and I've been told it's a number of things; Polish, Ukrainian, German and Russian. My great grand father was Piotr and his father Plato. Could someone help me and clarify it's origin? I know that Piotr was born in Mlawa, Poland but I don't know where Plato was born. Thanks.

(Alternative spelling could be either Teresco or Terescko)