How many spies were killed in the American Civil War?

Spies were common in the civil war, ranging from male to female, confederate to union. Many died, if a spy was caught they were hung most likely after being questioned with what information they knew. Both the North and South had a number of spies, they relied on them. The Civil War was a very spy consis war. As to how many were killed, I don't really know. Sorry..