Triptych is a 2006 thriller novel by American author Karin Slaughter.
 The first in her Atlanta series, the novel stars Will Trent of the Georgia Bureau of Investigation, and features Angie Polaski.
The Georgia Bureau of Investigation (GBI) is the U.S. state of Georgia's state bureau of investigation.
 It is an independent, statewide agency that provides assistance to Georgia's criminal justice system in the areas of criminal investigations, forensic laboratory services and computerized criminal justice information.
 Its headquarters is located in unincorporated DeKalb County, near Decatur and in Greater Atlanta.
DeKalb County ( ) is a county in the U.S. state of Georgia.
 As of the 2010 census, the population was 691,893, making it Georgia's fourth-most populous county.
 Its county seat is Decatur.
On September 16, 2017, Scout Schultz, a 21-year-old student at the Georgia Institute of Technology, was shot dead by Tyler Beck, an officer of the Georgia Tech Police Department.
 Schultz was carrying a type of multitool which includes a small knife.
 The incident was followed by protests and civil unrest, which led to multiple arrests.
 The shooting is being investigated by the Georgia Bureau of Investigation.
Vernon M. Keenan is the director of the Georgia Bureau of Investigation (GBI), that state's primary investigation and law enforcement agency.
Fractured is the second novel in the "Atlanta" series from bestselling author Karin Slaughter.
 The first book is "Triptych".
 This book was published in 2008.
 These books star Will Trent, a dyslexic Georgia Bureau of Investigation agent.
 The books also feature Angie Polaski and Faith Mitchell.
 Slaughter also writes the Grant County series.
 The audiobook is narrated by Phil Gigante.
Dr. Daniel S. Papp (born 1948) is an American scholar of international affairs and policy.
 For more than four decades, Papp served in a variety of professorial and administrative roles in the University System of Georgia (USG) (1973 - 2016).
 From 2006 to 2016, Papp served as President of Kennesaw State University (KSU), the third-largest university in the State of Georgia.
 During Papp's tenure, the University's enrollment increased by approximately seventy-five percent, growing from 19,854 to 33,252 undergraduate and graduate students.
 Under Papp, the University also significantly increased its research and graduate profile, adding a number of new academic programs (including eleven (11) doctoral degrees) and becoming classified as a Doctoral University with Moderate Research Activity.
 In Fall 2015, a University employee alleged the University's director of food services was engaged in fiscal misconduct, leading to an investigation by the Georgia Bureau of Investigation and USG.
 Investigations uncovered evidence the University's business office and external foundation were not consistently following USG financial procedures and mandatory reporting of financial misconduct policy.
 Termination of several high-ranking University employees followed.
 The investigation also contended the University's external foundation prematurely disbursed approximately $577,000 Papp earned in deferred compensation.
 While there was no evidence Papp approved or was aware of improprieties, on May 10, 2016, Papp announced his retirement.
Tara Faye Grinstead (born November 14, 1974) was an American beauty queen and high school history teacher who lived in Ocilla, Georgia and has been missing since October 23, 2005.
 Over the span of a decade, it became the largest case file in Georgia's history.
 On February 23, 2017, a press conference was held by the Georgia Bureau of Investigation (GBI) formally announcing that a tip had been received, leading to the arrest of Ryan Alexander Duke for the murder and concealment of Tara Faye Grinstead.
 In addition, on March 3, 2017, a supplementary arrest was made public in connection with Tara's disappearance: Bo Dukes (a former classmate of Ryan Alexander Duke, with no familial relation) was charged with attempting to conceal a death, hindering apprehension and tampering with evidence.
Terri Rachals is a former nurse from Georgia who was accused of killing people at Phoebe Putney Memorial Hospital in Albany, Georgia with potassium chloride, a heart-stopping drug.
 While suspected of killing at least nine of her patients, she was charged with only six murders, three of which she acknowledged possibly committing while in "Fugue state" in a recanted confession that she made to the Georgia Bureau of Investigation.
 Her trial, held in 1986, found her guilty on one of twenty aggravated assault charges.
 The other nineteen charges, as well as the ones for murder, were dismissed after a psychiatrist testified that she suffered from depression and other disorders that made her unaware of what she was doing.
Will Trent is the fictional main protagonist in author Karin Slaughter's Georgia Bureau of Investigation Atlanta series.
 Other major characters are Angie Polaski and Faith Mitchell.
 Current books in the series have the US titles of Triptych, Fractured, and Undone.
 Slaughter also writes the Grant County series.
 She has over 17 million books in print and is published in 30 languages.
 Some of her book titles differ in the US and other countries.

Question: What was the population in 2010 of the county in which the Georgia Bureau of Investigation is headquartered?
Answer: 691,893