John Sandford at home in Stillwater.

John Sandford has been writing his thrillers for 20 years. And today his publisher, G. P. Putnam & Sons, has announced the acquisition of two more Sandford novels: the fourth Virgil Flowers book, due out next fall, and "Storm Prey," the 21st novel in the "Prey" series, to be published in May 2011.

Sandford's first book, "Rule of Prey," published in 1989, introduced the character of Lucas Davenport, an agent for the Minnesota BCA.

Sandford's real name is John Camp, and he a Pulitzer Prize-winning journalist living in Stillwater.