Nearly 20 speakers at the dinner, which included a bevy of politicians, judges, lawyers, and police, applauded Carroll's quiet commitment to accomplishing that goal.
Chester County Court Judge Anthony A. Sarcione, Carroll's predecessor and a 30-year associate, said Carroll's influence in the District Attorney's Office started long before he assumed the top post 10 years ago. Calling Carroll the "go-to guy" on state statutes, Sarcione said, "He knew it all better than anyone else."
First Assistant District Attorney Patrick Carmody described a "bizarre combination" of humility and ambition. On the one hand, "Joe wanted to save the world." On the other, if Carroll forgot his county ID card, he would stand in line at the justice center's X-ray machine rather than pull rank to bypass the screening, Carmody said.
"He was a workhorse, not a show horse," Chester County Commissioner Kathi Cozzone said.
Carroll, a West Chester native, said he was honored by the accolades. During a subsequent interview, he reflected on his career, which began in 1975 when he was hired by the District Attorney's Office as an intern while attending law school at Villanova.
He flirted briefly with becoming a police officer, but decided he lacked the fortitude. He also ran several successful businesses, including a Coatesville pizza shop. That stint enabled him to deliver pizzas and an argument to the state Supreme Court on the same day when he was an assistant district attorney.
"It didn't seem odd at the time," Carroll said. "That was my life back then."
Ultimately, work as a prosecutor prevailed, even though being a pizza purveyor proved more profitable. He credited his wife, Barbara, and their two children, Joseph and Jennifer, with allowing him to pursue his dream.
Carroll, who was acting district attorney after Sarcione resigned to join the Chester County bench, was appointed to the top spot in January 2002. He ran for election twice - in 2004 and 2008 - winning four-year terms.
By then, Carroll had already worked on the Johnston brothers' prosecution, a high-profile set of convictions in the late 1970s and early 1980s for a gang that murdered six, spawned a Hollywood movie, and generated a series of appeals that continue today.
"That case won't die until all the defendants do," Carroll predicted.
Peggy Gusz, executive director of the Crime Victims' Center of Chester County, praised Carroll's impact.
"He touched the lives of countless victims with his compassion and keen belief that they deserved justice and deserved to be treated with dignity and respect," Gusz said. "Joe never faltered from this ideal, and his example set the tone for his office."
Some of Carroll's fondest memories involved his staff.
"Watching some of these kids evolve into accomplished prosecutors and seeing them realize that they were able to make a positive difference in a community, that was special," he said.
Carroll attributed dips in the county's crime rate and prison population during the last decade to a strong team of law enforcers and a number of prison alternative programs, such as drug and mental-health courts.
Known for his low profile, Carroll broke that pattern infrequently. The most dramatic example was in late 2008, when he lashed out at officials in Coatesville - Chester County's impoverished crime capital - for ignoring public safety.
Carroll bought a house in a drug-infested neighborhood, began rehabbing it, invited residents to a weekly open house on safety issues, and urged them to overhaul their government.
"I think the efforts made a difference for a while," he said, adding that he hoped the city would not cut police officers again to balance the budget.
Carroll said he hoped to sell the refurbished Coatesville house.
Only when prodded, he acknowleged that plan was on hold because someone "down on his luck" was living there.
Carroll said he was not ready for permanent retirement, and he knows his next venture will involve some type of public service. In the meantime, he will become more active in Camp Cadet, a weeklong, residential children's camp run by the state police; and at United Way, where he serves on the board.
"Right now, I'm enjoying today," he said.
Contact staff writer Kathleen Brady Shea at 610-696-3815, firstname.lastname@example.org, or @brandywinebits on Twitter. Read her blog, "Chester County Inbox," at www.philly.com/chescoinbox.