When did John Roberts transfer from CBS News to CNN?

There was a thread here recently, where some of us Canadians remembered things about the old days of radio and TV there. Someone mentioned news anchor John Roberts, and we remembered when he was disc jockey J.D. Roberts on CHUM and later, one of the first video jocks on “Toronto Rocks,” before MuchMusic was invented. Many years later, he moved to the US and was seen anchoring the evening news on CBS. This morning, I saw him anchoring on CNN.

Does anybody know when the move happened? Or why? (I suspect a bigger paycheck.) Just curious…

When Katie Couric got picked for Evening News anchor over him, he saw that he had no future at CBS. He left soon after.

I don’t know, considering how CBS Evening News ratings are doing…