A New Jersey man was arrested Saturday in connection with the deadly shooting in Jersey City last week that left four people dead — after investigators found his phone number tucked in the pocket of one of the two gunmen who opened fire on the Jewish market.

Ahmed A-Hady, 35, of Keyport, was taken into custody by FBI agents and charged with possessing a firearm while being a previously convicted felon, the U.S. Attorney's Office for the District of New Jersey said in a news release.

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Two suspected shooters — David Anderson, 47, and Francine Graham, 50 — killed four people on Tuesday, according to officials who have described the attack as an anti-Semitic hate crime that is now being investigated as domestic terrorism, and they were both found dead after an hours-long shootout with police.

In Anderson's back pants pocket, law enforcement found "a handwritten note" that contained a phone number and address in Keyport, N.J., a town roughly 35 miles south of Jersey City, that ultimately led investigators to A-Hady. The phone number was his and the address was that of a pawnshop storefront.

The U.S. Attorney's Office said A-Hady was found to have purchased Smith and Wesson .45-caliber and .44-caliber firearms in 2007 following a conviction for attempting to obtain a controlled dangerous substance or analog by fraud in 2012. Because of that conviction, he was banned from owning firearms.

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Inside a safe at the pawnshop on Friday night, investigators found three weapons, including the .44-caliber handgun, and recovered six rifles — including three AR-15-style rifles — three handguns and a shotgun. Authorities also recovered 400 rounds of ammunition, including "a large number of hollow-point bullets."

A-Hady's relationship with the shooters was not immediately clear.

Investigators said Anderson and Graham, who appear to have acted alone even though they had expressed interest in the Black Hebrew Israelites, a fringe religious group that often disparages whites and Jews, killed Jersey City Detective Joseph Seals at a cemetery when he reportedly recognized the two as suspects wanted in the December 7 murder of an Uber driver.

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Anderson and Graham also killed Mindy Ferencz, who co-owned the JC Kosher Supermarket, Moshe Deutsch, who was buying a sandwich at the market, and Douglas Rodriguez, who was an employee at the store.

Steven Fulop, the mayor of Jersey City, suggested on Twitter Friday the gunmen may have actually targeted 50 children at a Yeshiva school attached to the supermarket.