It wasn't the first time he'd made history; that happened in 2010 when he became Wisconsin's first black district attorney.
Eventually, Ozanne told reporters that he'd cleared Matt Kenny of the Madison Police Department, declaring that the officer's gunfire was "a lawful use of deadly police force."
But before he revealed his long-awaited decision Tuesday, the prosecutor also made it a point to talk about his past.
Ozanne is no newcomer to Wisconsin or its politics. A sixth-generation Wisconsonite, he hails from a pro-union family in an increasingly anti-union state and unsuccessfully ran for attorney general as a Democrat in last year's primary.
Here are five things to know about the latest local prosecutor to garner national attention in a controversy over a police shooting:
Wisconsin's first black DA
Ozanne became the first African-American district attorney in Wisconsin history
in August 2010, when former Wisconsin Gov. Jim Doyle, a Democrat, appointed him as Dane County district attorney.
Ozanne's appointment filled a vacancy created when the prior DA was elected as a Court of Appeals judge.
At the time, Ozanne had been a top aide in Doyle's Cabinet, specifically in the Department of Corrections.
Ozanne then ran unopposed in 2012, winning that election in the state's second largest county. Ozanne is married to Stacy Nichols Frank Ozanne, a real estate agent, and the couple have two small daughters.
"I am a man who understands the pain of unjustified profiling, and I am the first district attorney of color not only in Dane County, but in the state of Wisconsin," Ozanne said Tuesday. "I make note of this because it is through this lens that I approach and accept my leadership responsibilities."
Deep Wisconsin roots
Six generations ago, Ozanne's family arrived in Wisconsin in the late 1800s
and settled in Neenah, Wisconsin,
which at the time was home to flour mills, the lumber industry and paper mills.
Neenah's location on the Fox River attracted
those industries back then, and in fact, paper mills continue to play an important role in that city.
Ozanne's grandfather, Robert Ozanne, was a high school teacher, a labor organizer, an author and a professor of economics at University of Wisconsin at Madison in the 1950s, according to Ismael Ozanne's biography.
His parents are also teachers: His father taught at Tuskegee University in Alabama and in Madison public schools, and as of last year, his mother was still in the classroom, teaching reading at a middle school.
Ozanne describes himself as biracial.
"I'm a person of color from a biracial marriage. ... I am the son of a black woman who still worries about my safety from the bias and privilege and violence that accompanies it," he said Tuesday.
Prosecutor since the 1990s
After graduating with his law degree from UW Madison in 1998, Ozanne began his career as a prosecutor as an assistant DA.
While in school, Ozanne played soccer at West High School in Madison and at the state's flagship university, "leading West to two state titles and lettering as a freshman for the Badgers," his biography says.
As prosecutor, he initially handled civil traffic cases and then moved up to first-degree intentional homicides. For almost eight years, he handled domestic violence case, and then he was assigned felony drug cases.
On Tuesday, he pointed out that he's bound to the oath he took to uphold the Constitution of the United States of America, and Wisconsin's state Constitution -- and "cognizant of the very real racial disparities and equity issues which exist in this county."
Labor advocate who joined Democratic governor's Cabinet
Following in his grandfather's footsteps as an advocate for labor, Ozanne represented the Association of State Prosecutors, the union for assistant DAs, as an executive board member, a bargaining committee member and a union representative in his office.
In February 2008, Doyle appointed Ozanne to be the executive assistant for the state's Department of Corrections, the largest Cabinet agency, and Ozanne worked on the department's $1.2 billion budget.
A year later, Ozanne was promoted to deputy secretary, in charge of daily operations.
Those posts were the No. 3 and No. 2 political appointment in the DOC, the Milwaukee Journal-Sentinel reported.
He ran for attorney general last year
Though a defeat, the campaign marked something of a personal family triumph.
Ozanne campaigned with his mother, Gwen Gillon, who was the youngest member of the Student Nonviolent Coordinating Committee during the 1964 Freedom Summer.
And he pointed to his mother's background with pride at Tuesday's news conference.
SNCC began as a nonviolent civil rights group but later advocated greater militancy in the mid-1960s as part of the "black power" movement, according to Encyclopedia Britannica.
Ozanne's mother "went throughout Mississippi registering people to vote, knowing she could lose her life," Ozanne said, according to the State Journal.
Ozanne cited his mother's participation in his campaign as a personal highlight.
"One of the most special and sort of battery-charging things about this campaign was being able to go with my mother, who was in 1964, the youngest member of SNCC, at 17, going through Mississippi, registering people to vote, risking her life," Ozanne told supporters after losing last year's primary, according to the Isthmus news outlet in Madison