B.C.
I've have great success with the Shout Advanced Gel...It says it's formulated for set-in-stains! I usually spray and let dry sometimes a day or so before washing...It's gotten grease stains from cooking out of my shirts I didn't know were there after the first wash a dry..
Someone mentioned peroxide, I've always used that on blood stains, works great as long as you don't let the blood dry (sometimes you might still need to soak the item) If it dries you have a chance you won't get it all out....
Good Luck
B.