Philadelphia District Attorney Larry Krasner’s office said Wednesday that a lack of witnesses appearing in court has been the biggest reason some illegal gun-possession cases have failed to end with a conviction over the last several years — a trend some have blamed for skyrocketing gun violence in the city.

Still, in written testimony submitted to members of City Council, Krasner said that staffers who studied about 400 such cases found that those issues had been generally steady since at least 2016 — leaving them unable to say why more gun-related prosecutions were being withdrawn or dismissed during Krasner’s administration than during his predecessors’.

“We continue to analyze what drove a higher dismissal and withdrawal rate in 2018-2019,” says the testimony, a copy of which Krasner’s office shared with The Inquirer.

About half of the cases studied, both pre- and post-Krasner’s arrival, were tossed primarily due to witnesses not showing up, according to the testimony. About a quarter failed due to “weak evidence.”

The report came in response to questions raised at Council hearings on gun violence during the year. Officials including Police Commissioner Danielle Outlaw had publicly cited data published by Krasner’s office showing that a higher percentage of illegal gun-possession cases had been getting dismissed — even as police were arresting more suspects for illegally carrying firearms, and as the city’s gun violence hit near-record levels in 2020.

Before Krasner was sworn in, according to data his office posted online, , the share of illegal gun-possession cases withdrawn or dismissed never topped 29%. But it has grown in each of the last three years — from 32% in 2018, to 42% in 2019, and 48% this year, according to the latest figures published Wednesday.

Some police commanders — who have long grumbled about what they perceive as Krasner’s leniency toward gun crimes — began waging a thinly veiled campaign of criticism on social media this fall as they apprehended gun suspects.

The debate was a more public extension of an issue that has been bubbling for years. Last summer, former Police Commissioner Richard Ross suggested that gunmen were increasingly carrying illegal guns because they believed they wouldn’t be held accountable even if arrested.

Around the same time, The Inquirer analyzed hundreds of gun-possession cases before and after Krasner took office, finding that convictions had declined under Krasner — almost entirely due to withdrawals or dismissals. His office pushed back against that analysis at the time.

This year, Mayor Jim Kenney waded into the fray, accusing Krasner of being too forgiving of suspected gunmen — an accusation the district attorney denied, saying that he was continuing to charge nearly all suspects arrested for violent crimes, and that he was also seeking high bails for those defendants.

In the testimony to Council, Krasner said his office studied about 400 cases that were withdrawn or dismissed and featured a gun-possession charge. The report did not include specific details about any cases, but Jane Roh, a spokesperson for Krasner, said some were considered robberies or aggravated assaults that also involved an illegal firearm. Those cases are generally prosecuted differently than mere gun possession, and feature a different array of potential witnesses, with different reasons for being hesitant about coming to court.

The reasons for failure in that sample were generally consistent before and after Krasner took office, the report said.

As for evidentiary problems, Krasner’s office reported that more cases in the last two years have suffered from so-called constructive-possession issues — when a gun is found in a car, for example, but there isn’t enough evidence to tie it to a specific person inside.

Krasner and Outlaw announced this month that their agencies have begun working more closely together to examine weekly arrests in gun-related crimes and identify possible issues with recent cases, such as what additional evidence might bolster a prosecution when it reaches court.