I did Google "walker death threats" and guess what -- your claim is false. Imagine that . . .
Among the links that came up on page 1 were the Huffington Post , TMJ4 (NBC television affiliate), the New York Daily News, WGBA-TV (NBC affiliate), and WISN TV (ABC affiliate).
And then there's this: Multiple law enforcement agencies investigating Walker death threats - Local News - Milwaukee, WI - msnbc.com