Using sarcasm followed by an argument fit for a prosecutor, Mayor Lori Lightfoot fired back at Toni Preckwinkle Thursday for the vanquished mayoral challenger’s attempt to exonerate county bail reform as a “root cause for gun violence.”

The sarcasm came when Lightfoot referred to what she called the “nice letter” she had received from Preckwinkle about the issue.

Clearly, the mayor believed otherwise and could not contain her anger about Preckwinkle’s very public attempt to discredit the crime-fighting argument made by Police Superintendent Eddie Johnson and by the mayor as well.

“It’s July — not March. The election’s over and we had a result,” Lightfoot said, referring to her 74 percent landslide over Preckwinkle in the April 2 runoff that saw Lightfoot sweep all 50 wards.

“We’re gonna continue to take the high road and move forward. But, there are legitimate issues that have been raised and the superintendent, I think, is right to raise them.”

Lightfoot then returned to her roots as a federal prosecutor with a point-by-point rebuttal of Preckwinkle’s argument.

She pointed to Fourth of July weekend, when 76 people were arrested for weapons-related violations, 18 of them repeat gun offenders; 10 of those repeat offenders had the “opportunity to get back out on the streets,” Lightfoot said.

Lightfoot said she’d like to “get rid of cash bond in its entirety.” She called it a “problem we need to solve at the state level.” But, the mayor also argued that it “matters how we’re making decisions” about when bail is set.

She noted that Cook County is now using a tool developed by the Arnold Foundation in Texas that’s based on a “range of criminal statistics nationally.” It’s not specific to Cook County and doesn’t count unauthorized use of a weapon, Lightfoot said, which she called a “very common charge” in Cook County.

“That’s obviously a problem,” the mayor said.

Regardless of the tool being used, Lightfoot said, the “equation” comes down to several fundamental questions: Is the offender a flight risk? Will that person show up again for court? And, are they a danger to the community?

“I submit to you that someone who has a long track record of gun violence and then is charged with another gun-related offense is, by definition, a danger to the community,” the mayor said.

Instead of pointing fingers and working “against each other,” all stakeholders should try to address the issue, because “lives are at stake,” the mayor said, adding that “judges have to use their common sense” about who gets out on bond.

Lightfoot said earlier this week she “feels like we’re losing the streets” after another violent summer weekend that saw 32 people shot and nine killed.

On Thursday, the mayor said she continues to push hard “for the pieces of this puzzle that we control” with “all hands on deck, flooding the zone, taking responsibility.”

But she argued “another piece” of that puzzle is “owned by various county actors and they have to be part of the solution as well” to confront Chicago’s cycle of gang violence.

In a high-stakes game of political poker, she’s challenging Preckwinkle to put her cards on the table.

“My proposal is that we all put our data out on a weekly basis and see who’s getting arrested. What are the charges? What are the bond decisions being made? And separately, if they’re out on bond … what [are] the results? Are they staying within the geographic boundaries that they’re supposed to? And if not, is there any follow up?” she said.

“We will put our data up. And I want the county to do the same on a weekly basis. That’s how we get to some answers.”

Preckwinkle gave no ground in a statement issued Thursday.

“This is about governance not politics, plain and simple,” she said.

“We can go back and forth all day about statistics. The public doesn’t care about spreadsheets, they care about solutions and results. I stand by my statement that false narratives do not help us achieve the goals of making sure all of Cook County is safe and viable. Nor does it save lives.”

As she did in her letter to the mayor, Preckwinkle invited the city to “come to the table and have a dialogue” with the county.

“Criminal justice reform is a priority and it is necessary. We must do all we can to reverse the devastating impact of mass incarceration of black, brown and poor people in this country; and, equally so, it is our responsibility as leaders to ensure that every resident has the ability to live in safe and healthy neighborhoods,” she said.

In her letter to Lightfoot and in a follow-up interview, Preckwinkle had argued that Johnson and the police union leading the charge against Preckwinkle’s ally and former chief of staff, State’s Attorney Kim Foxx, have “promulgated” a narrative that pins city violence on “county judges, county prosecutors — and their failure to do their job and that’s simply not true.”

She told the Sun-Times: “It’s a false narrative, and they know it, and it’s infuriating.”

Preckwinkle accused Johnson of pointing fingers to evade the root of the city’s crime problem: his department’s clearance rate for homicides, which she called “one of the lowest in the nation.”

Contributing: Rachel Hinton