Jackson admitted, Sheridan said, that he bought guns illegally in Ohio, brought them to New Jersey, and "resold them to others in exchange for cash."
Illegal guns "are part of the criminal underworld," said Camden County Police Chief Scott Thomson, whose force patrols the city. "They are being used in street crimes. They are being used by gangs to facilitate their drug trade and the violence that goes with it."
Thomson said he was not aware of Jackson or the federal case against him, but was all too familiar with the problem of illegal weapons, particularly in Camden.
"What experience has shown us in the city of Camden is, the vast majority of crime guns in the city do not come from the state," he said, noting that New Jersey has some of the toughest gun laws in the nation. "They are being funneled in from Pennsylvania, Ohio, and Virginia."
Thursday's federal criminal complaint against Jackson was accompanied by a seven-page, single-spaced affidavit from Sheridan.
In it, Sheridan says Jackson admitted to about 40 weapons deals during their jailhouse chat.
Sheridan says Jackson told him he had sold nearly all his inventory by July 31, 2010, when he had to report to prison, but left two items unsold.
Jackson, of Willingboro, is in prison on a state conviction for illegal possession of a firearm in 2008. He has other convictions for burglary, theft by deception, and credit-card fraud.
The investigation got its start, Sheridan wrote, when he and his colleagues at the ATF's Camden office "observed that an unusually large number of firearms that were recovered in crimes in Southern New Jersey had originally been purchased in the state of Ohio."
Working through informants and felons, Sheridan wrote, they began to trace the guns to Jackson.
Among the guns involved were a Ruger SR9 pistol and a Glock 26 pistol, the company's smallest, easily concealed.
According to the affidavit, Jackson worked as a middleman, buying as many as 245 guns from an associate in Ohio who illegally purchased them.
The associate told ATF agents, Sheridan wrote, that "Jackson quickly became his best client." Jackson would buy as many as 20 weapons and drive them in a rented white Dodge Charger to New Jersey or to customers in Pennsylvania, New York, or Massachusetts, and then drive back to Ohio the next day to buy more guns.
Another informant told agents that Jackson would drive the informant to gun shows in Ohio and wait outside, sending text messages about which guns should be bought.
If Jackson did not have the Charger, he or an associate would bring the guns from Columbus, Ohio, to Mount Laurel on Greyhound buses, packing the weapons in duffel bags and backpacks.
Jackson sold a lot of guns to a man who resold them in Camden, completing the deal at the Red Roof Inn in Mount Laurel, Sheridan wrote.
If convicted, he faces five years in federal prison and a $250,000 fine. He will have an initial appearance before U.S. Magistrate Joel Schneider on Friday.
Contact Jane Von Bergen at email@example.com, @JaneVonBergen on Twitter, or at 215-854-2769. Read her workplace blog at www.philly.com/jobbing