Today, he oversees an office with some 1,100 staff, including 500 prosecutors handling more than 115,000 misdemeanor and felony cases a year.
Both challengers have prosecutorial experience, but neither has ever run for public office.
Thompson, 46, is a former assistant U.S. attorney in the Eastern District, where he obtained the high-profile conviction of a New York City police officer charged with beating and torturing Haitian immigrant Abner Louima. Another officer pleaded guilty during trial.
In private practice, Thompson represented Nafissatou Diallo, the hotel maid who claimed she had been raped by former International Monetary Fund chairman Dominique Strauss-Kahn. After the Manhattan District Attorney's Office dropped the criminal case, Thompson obtained a civil settlement for her.
Thompson's mother, Clara, was one of the first women on patrol in the New York Police Department, serving in Harlem and the Bronx.
His mother's 21-year NYPD career gave Thompson "a powerful example of courage and sacrifice, justice, equality and fairness" that he says he carries with him and explains why he "stand[s] up for people who need justice."
Thompson plans to roll out more specifics about his plans in the coming months, but, for now, he says gun violence will be among his top priorities. He also said he would create a unit to prosecute labor law violations and promised to bring the "best and brightest" prosecutors to Brooklyn.
He also criticized Hynes for an "unacceptable" felony conviction rate of 55 percent in 2011. Hynes said focus on that statistic alone is misleading because many dismissals are granted where defendants participate in alternatives to incarceration.
George, 34, is the son of Indian immigrants and a lifelong Brooklyn resident. He worked in the Manhattan District Attorney's Office for eight years before resigning last summer to focus on the campaign.
At one point he was assigned to the Office of the Special Narcotics Prosecutor and handled cases citywide, giving him a look at law enforcement in Brooklyn. He said Hynes' office is presiding over "revolving door" justice where people are arrested, convicted and released to commit more crimes.
George said he would prosecute low-level marijuana possession cases as violations and demand that police officers personally swear to arrest complaints to counter an "excessive" number of criminal cases arising from police use of the stop-and-frisk technique.
Thompson called stop-and-frisk tactics "a valuable law enforcement tool if used right." But both he and George criticized Hynes for not speaking out about purported overuse of the practice.
Hynes "has never once said a single word about whether this practice is right or wrong," Thompson said in a statement, pointing to more than 56,000 stops that occurred in East New York and Brownsville in 2011"most of whom were young men of color who had done nothing wrong."
Hynes said stop-and-frisk policies are "a police decision" over which he has "no control." But he said he is trying to lessen "anxiety" for teens and their parents when the teen is "unnecessarily arrested" for low-level marijuana possession.
Hynes said his office offers an adjournment in contemplation of dismissal in such cases and is working with the courts and the police to have those dispositions handled quickly at precincts rather than at the courthouse.
As district attorney, Hynes has instituted about 30 programs that provide alternatives to incarceration and ease community reentry for former inmates.
"The easiest thing we do is put people in jail," he said. "It does not take a lot of intellect."
Dawn Ryan, attorney-in-charge of the Legal Aid Society's criminal defense office in Brooklyn, said Hynes' office has "emphasized the importance of community outreach" and has "collaborated" with the defense bar, churches and various public entities.
He is also credited for his office's open-file discovery policy, viewed as the "best" in the city, said Barry Scheck, codirector of the Innocence Project and a professor at the Benjamin N. Cardozo School of Law.
If reelected, Hynes said he will expand community courtsestablishing one in Brownsville in two years and scouting a location for another to add to the current Red Hook courtand broaden eligibility for his reentry programs.
Both Thompson and George said that, if elected, they would examine the benefits of each program.
"Whatever is effective, obviously we intend to continue and improve," said Thompson.
Likewise, George said he would "keep everything that's working," pointing to the open-file discovery, alternatives to prison and reentry.
But while crediting Hynes for "some progressive programs," George said "the bad outweighs the good" in the way Hynes has run his office.
The challengers and other critics take a negative view of how Hynes has handled sexual abuse within the ultra-Orthodox Jewish community, accusing him of soft-pedalling the problem at the behest of politically powerful rabbis. A 2008 editorial in Jewish Week, for example, charged that his stance ranged from "passive to weak-willed."
In 2009, Hynes established Kol Tzedek, which strives to encourage victims of sexual abuse to come forward. But he has been criticized for declining to publicize the names of defendants in pending matters and sometimes after their conviction. (Cases occur in open court on a public calendar, and the office will confirm that individuals face charges if asked.)
Both Thompson and George hammered Hynes on his approach.