People charged with gun offenses have been increasingly getting out of jail on electronic monitoring since bond reforms were launched last year at the Cook County courthouse at 26th and California, according to an analysis by Sheriff Tom Dart’s office that warns of a potential threat to public safety.

Over a three-month period in late 2016, nearly all of the gun defendants who passed through the courthouse got a “D” bond, meaning they had to put up 10 percent of a cash amount to make sure they’d return to court.

But half of the gun defendants in late 2017 were either released on electronic monitoring or on “I” bonds that don’t require them to put up any money, the sheriff’s study showed.

On Thursday, Dart sent a letter to Cook County President Toni Preckwinkle and other county officials calling those findings “alarming.” He pledged to boost the supervision of gun defendants being released into the community on electronic monitoring.

“This needs to get fixed quick,” Dart said in an interview.

He said he will reach out to the judiciary to seek a solution.

“I am very concerned about it,” echoed County Commissioner Richard Boykin, who represents the violence-plagued West Side.

Boykin is calling for a hearing with Dart, Chief Judge Timothy Evans, State’s Attorney Kim Foxx and Public Defender Amy Campanelli to “get a true accounting of this.”

“I am for criminal-justice reform and reducing the number of people who are in our county jail, but there is a big difference between those arrested on gun charges and those arrested for stealing candy bars.”

“Electronic monitoring should be for individuals who are not a risk to the general public,” Boykin said.

In September, major changes were made in the way bonds are set at the Leighton Criminal Court Building.

The reforms came on the heels of a lawsuit that questioned the constitutionality of the bond system at the courthouse.

They also followed the passage of the state Bail Reform Act that took effect in June. The law says judges should try to find an alternative to cash bail when someone is charged with a nonviolent offense.

In July, Chief Judge Evans signed an order “intended to ensure no defendant is held in custody prior to trial solely because the defendant cannot afford to post bail.”

He replaced the six judges who presented over bond hearings at the courthouse at 26th and California. He installed judges who were trained to use an assessment tool to make bond decisions.

The sheriff’s analysis shows that those new bond-court judges — unlike their predecessors — usually have adhered to the bond recommendations generated by the assessment tool.

And their resulting bond decisions have been starkly different than their predecessors.

In felony gun cases, 96 percent of the gun defendants studied in 2016 were given cash bonds. Most of the bonds ranged $40,000 to $99,000. Just 2 percent of those defendants were placed on electronic monitoring and only 2 percent got no-cash I bonds.

In 2017, though, only 40 percent of the gun defendants got cash bonds. And most of those bonds were for less than $10,000. Meanwhile, 22 percent of the gun defendants were placed on electronic monitoring and another 28 percent got I bonds.

The study looked at 261 defendants in 2016 and 322 of them in 2017. Their cases included various gun-possession offenses, aggravated battery, aggravated assault, reckless discharge of a firearm and selling a gun without a state firearm owner’s identification card.

In his letter to county officials, Dart said he plans to have the sheriff’s office review the criminal histories of gun defendants ordered released on electronic monitoring.

“Those who are deemed to be too high a security risk to be in the community will be referred back to the court for further evaluation,” he wrote.

He said he also plans to assign more employees — 10 to 15 — to his community corrections division to boost oversight over electronically monitored gun defendants. Those admitted to the program will have unannounced searches of their homes, Dart said.

His office has created a map showing the addresses of gun defendants on electronic monitoring. Most are returning to Chicago neighborhoods plagued with violent crime.

“The numbers are clear,” Boykin said. “Most of the violent offenders are being sent back to the West Side district I represent.”

Dart also said he intends to push again for legislation in Springfield that would allow judges to withhold bond for gun-possession defendants with violent backgrounds. Currently, gun possession isn’t considered a violent offense legally, and it’s not among those crimes for which judges can hold people in jail without bond until trial, he said.

Pat Milhizer, a spokesman for Evans, stressed that “the population we are talking about is pretrial defendants who are presumed innocent until proven guilty.” He said that numbers his office has gathered on people released from jail on electronic monitoring or I bonds indicate that most of them aren’t public-safety threats.

Evans’ office studied pretrial defendants released between Oct. 1, 2015, and March 31, 2017. Milhizer said 82 percent of them weren’t charged with a new crime through Dec. 31, 2017, while their cases were pending.

Over the same period, he said, 97 percent of gun defendants didn’t have a “violence flag” in their pretrial assessment score for bond.

Still, Dart’s aides said they suspect that gun defendants are committing new firearm offenses while on electronic monitoring and out on I bonds. But the aides say they don’t know the extent of the problem.

That’s because few shooters in Chicago get caught. The Chicago Police Department made arrests in fewer than 5 percent of nonfatal shootings in 2016, records show.