Who wrote the books that was basis for The Shooter?

The film "The Shooter" is based on the 1975 novel "Point Blank" by Donald E. Westlake, who wrote under the pseudonym Richard Stark.

It's important to note that "The Shooter" is not a direct adaptation of the novel. It's more of a loose adaptation, borrowing some key elements from the story but with significant changes to the plot, characters, and themes.