Juno mourned Starkiller as dead...but now he is back, purged of all memories and programmed to kill. And as fate brings Juno and Starkiller closer to reuniting, with Darth Vader determined not to lose his assassin a second time, they will both have to make a stand. The prize is freedom. The punishment for failing will be eternal enslavement to the dark side of the Force...
This is an entry from the Amazon product page for the book. Alot say the books are just as canon and i agree. this shows that starkiller is most likely alive just purged of memory similar to Revan