The marching orders came down from Washington: Boost prosecutions of federal gun cases, especially those involving drug dealers and gang members.

In Mobile, Alabama, the federal prosecutor charged with carrying out the directive, known as Operation Triggerlock, did so with zeal. In 1991, Jeff Sessions, then the U.S. Attorney for the Southern District of Alabama, prosecuted 31 gun cases — up from zero the year before. Over a three year span, Sessions’s office would prosecute nearly every gun case referred to it.

“His office was pretty aggressive,” said Donald Partridge, who worked as a defense attorney in federal court in Mobile at the time. “It was my understanding that if there was any indication a gun was used, that they were gonna pursue it.”

On Wednesday, Sessions was sworn in as Attorney General of the United States. He assumes the post at a time when violent crime is significantly less prevalent than when he was a federal prosecutor — but when homicide, especially gun homicide, is on the increase in many major American cities. He serves a president who has sworn to restore “law and order.”

During the confirmation process, Sessions signaled that he intends to revive the tough-on-guns prosecutorial approach of his past. More gun charges — especially those that carry stiff, mandatory five-year sentences — will send a message to those who are pulling the trigger that they are best off leaving their guns at home, he has argued.

“Criminals are most likely the kind of person that will shoot somebody when they go about their business,” Sessions said during his confirmation hearing. “And if those people are not carrying guns because they believe they might go to federal court, be sent to a federal jail for five years, perhaps they’ll stop carrying those guns during that drug dealing and their other activities that are criminal. Fewer people get killed.”

The Trace reviewed the 70 gun cases that then-U.S. Attorney Sessions brought against criminal defendants in his busiest year, 1993. The cases are more than a quarter-century old, and the implementation of any order from a Sessions-led Justice Department to prosecute more gun cases would be up to a new crop of federal prosecutors to implement. But the analysis shows how Sessions himself carried out an order of the type he has signaled he is likely to issue.

Sessions’s office was able to make lots of gun cases in a few short years, and some of those who were charged were exactly the type of offender that Sessions has said he wants to think twice before leaving home with a gun in their belt. But in most cases, gun charges were piggybacked on top of another type of charge, usually a drug violation, sometimes substantially lengthening what would have otherwise been a short sentence.

A significant share of the cases involved so-called felon-in-possession: people with criminal records caught with a firearm. Other cases seemed to have involved federal lawyers picking through state records to identify people with criminal records fined for violating hunting ordinances.

Jim Burch, vice president for strategic initiatives at the Police Foundation, a nonprofit law-enforcement think tank, said taking “a shotgun approach” to gun prosecutions yields “an unsustainable level of incarceration” — and would not effectively target or deter “the people committing or contributing to violent crime.”

Of the 70 gun cases that came out of Sessions’s office in 1993, just 19 were tied to a clearly violent crime. Those cases carry the biggest penalty: a mandatory five-year sentence that must be served after completing the sentence for the underlying crimes. The charge functions as what lawyers call a “tack-on” that substantially increases prison time, or the sentence prosecutors can threaten in order to secure a guilty plea in cases that would have been prosecuted regardless.

Gerry Sanders, indicted September 23, 1993 in federal district court in Mobile for bank robbery, received an eight-year sentence — three for the robbery, five for using a gun. Marvin Osbey received a 10-year sentence for a 1993 carjacking and five more years for possession of a gun during the crime. David Hodge and Randy Powell, charged in an armed bank robbery in 1993, both pleaded guilty to gun charges, drawing five-year sentences, while dismissed the bank robbery charges. There is no record in the case dockets that any of the 19 men fired weapons during their crimes, actions that would have carried additional punishment.

Sessions also took frequent advantage of a 1986 law that allows prosecutors to add gun charges on top of already-stiff mandatory sentences for drug trafficking. In 1993, his office pursued 11 cases in which using a gun in a drug deal had a mandatory sentence of five years. If the defendant carried a gun in two transactions, even on the same day, prosecutors in a single case could charge that person as a “repeat offender,” with penalties from 25 years to life.

Sessions’s office used this statute to increase the sentences of dealers accused of carrying weapons while trafficking dozens of kilograms of cocaine across state lines, against defendants accused of possessing gun while selling marijuana, and against defendants caught attempting to buy crack and found to have a weapon on them. Benny Ray Harness was sentenced to five years in November 1993 for carrying a gun during a drug transaction. He was originally also charged with attempt to possess crack cocaine with intent to distribute but the drug charge was dropped when he took a plea deal.

At the time, prosecutors in Sessions’s office drew notice for relying heavily on the testimony of informants who implicated others to reduce the long sentences they themselves faced. A 1999 PBS documentary, “Snitch,” focused largely on the use of informants by the U.S. Attorney’s office in Mobile under Sessions and his successor.

“Of all the places I’ve been, I think that district was especially draconian in seeking high sentences and dragging a lot of people in that probably didn’t need to be in federal court,” said Alex Bunin, who became chief federal defender in the district in 1995, working on many cases still active from the early 1990s.

Bunin said many of gun cases prosecuted under Sessions would have been left in state courts in other districts, where sentences were generally more lenient.

“Any drug case where there was a gun, they would tack on a gun charge,” Bunin said. “Those made great stats and really jacked up the sentences.”

Many of those convicted under Sessions in the early 1990s on drug and gun charges remain in prison today. One of them, Lawrence Powe, convicted in 1992 at age 26 for drug trafficking, was among the 1,715 offenders granted clemency by President Obama before leaving office. Powe, a father of four given a life sentence for selling crack cocaine (which was later reduced to 35 years), received two additional five year sentences — to run simultaneously — for “use” of a gun. Those gun charges were based on claims by a confessed drug dealer who cooperated with Mobile police after he was arrested with crack and a gun in his car. The dealer told police that Powe gave him .38 caliber guns to use for protection while selling drugs.

In one of dozens of failed motions for a sentence reduction citing his unblemished disciplinary record in four federal institutions, Powe wrote in 2008 that he was having “some fast fun and enjoying some fast money” at the time, but was “not a murderer.”

At least three cases were brought against those selling stolen or unregistered guns, federal charges that can be used to prosecute gun trafficking. (In his Attorney General confirmation hearings, Sessions promised to prioritize the “reduction of illegal interstate trafficking of firearms,” despite the fact that there is no federal law that explicitly bans such activity.)

The gun cases most commonly prosecuted under Sessions came under a section of the 1968 Gun Control Act that bars convicted felons from possessing guns. According to current and former federal law-enforcement officials, these cases are generally seen by U.S. Attorneys’ offices as too minor to spend much time on, but an easy way to boost their total number of gun prosecutions.

“They tend to be on and off, like a spigot,” said Arthur Madden, a longtime prosecutor in Mobile. “You can just do those forever, just taking cases from the state.”

Sessions’s office did not record prosecuting any cases in which felon-in-possession of a firearm was the lead charge between 1986 and 1990, records show. In 1993, it pursued cases against 25 defendants on felon-in-possession charges. Eighty percent of those defendants were were not accused of other crimes.

Lawyers in southern Alabama said those defendants were likely caught by federal officials reviewing state court records for infractions like hunting violations by people with felony records, and were then charged in federal court.

“ATF would see if they had any felons in possession in the district,” said E.T. Rolison, who spent 35 years as a senior prosecutor in the Southern District of Alabama before retiring in 2010. “That’s the way the cases got the U.S. Attorney’s office.”

The felon-in-possession cases were easy for prosecutors to find, but actual outcomes were mixed. Some of the defendants charged served four- or five-month sentences after plea deals. Others received sentences of three years or more and, in many cases, returned to prison after their release because of parole violations. For example, in August 1993, Gene Ware was sentenced to 37 months on felon-in-possession charges. He was paroled in 1996 on the conditions that he avoid firearms, drugs, and alcohol — but his parole was revoked the next year, and he was returned to prison for 24 months.

Sessions was hardly the only federal prosecutor making lots of gun cases in the early 1990s. But his office was more aggressive than most. From 1991 to 1993, his office prosecuted 90 percent of gun cases referred by law enforcement, according to data from the Transactional Records Access Clearinghouse. Between 1994 and 2004, the decade after Sessions had served as U.S. Attorney, his former office accepted 65 percent of such cases.

“It was all stat driven,” Rolison said. “There was nothing sinister about it, but when the Attorney General or the U.S. Attorney put an emphasis on something, they’d pass it down to guys like me.”

Rolison said the office prosecuted gun cases before 1991, but “only started counting” them — and increased the number of cases prosecuted — once Washington began pushing U.S. Attorneys for more firearm prosecutions in the early 1990s. (The current U.S. Attorney for the Southern District of Alabama and the Department of Justice declined to comment.)

The federal gun statutes that federal prosecutors in Mobile wielded under Sessions remain on the books. Obama’s first Attorney General, Eric Holder, instructed U.S. Attorneys to exercise discretion regarding how they prosecute gun cases, undoing guidance that required them to prosecute gun charges in federal court whenever possible.

Holder specifically told federal prosecutors to generally avoid using charges that included a mandatory five-year sentence to pressure defendants to plead guilty. After that directive, such prosecutions fell. The total number of federal firearms-violations cases cases filed by U.S. prosecutors in fiscal year 2015 was 8,528, down from 11,067 in FY 2004, according to annual statistical reports issued by U.S. Attorney offices.

Sessions criticized Holder’s efforts at the time. Now, as Attorney General, Sessions is tasked by President Trump with taking on “carnage” in cities, and can push federal prosecutors to resume the kinds of prosecutions he himself carried out as a U.S. Attorney. Lawyers familiar with Sessions’s record in Alabama have little doubt he will do so.

Local police groups and elected officials representing cities that are grappling with gun violence have said they’d prefer the Justice Department provide more resources for local policing efforts. They’d also welcome the help of federal prosecutors, so long as gun charges don’t simply become a numbers game: A recent report from the Police Foundation concluded that “the greatest value in reducing violent crime may come from the strategic and realistic threat of federal prosecution, rather than the actual number of firearms prosecutions.”

Major-city police chiefs, surveyed as part of the report, ranked more “enforcement resources” as the most important way the Justice Department can assist them in addressing crime.

“The response to local violent crime problems must be based on the specific problem identified in the local area, not merely on what federal agencies have identified as national problems,” the report said, warning against efforts that “cause an undue strain on resources (e.g., mass incarceration).”

Daniel Richman, a law professor at Columbia University who worked as federal prosecutor in the U.S. Attorney’s Office for the Southern District of New York, said Sessions might move in the direction that law enforcement has asked for, and facilitate federal partnerships, like embedding FBI or ATF agents in local homicide units.

Richman said it is uncertain what impact an increase in prosecutions like those Sessions pursued in Mobile would have on their own.

Gun prosecutions “can cover a range of people,” he said. “You are getting someone with a gun, and that’s something, but the likely effect on violence is far from clear.”

Maura Ewing contributed to this report.