JACKSONVILLE, Fla. – Across the state of Florida, Jacksonville had the most guns recovered last year that were tied to crimes -- more than 4,000 in 2014 and 2015 combined, the News4Jax I-TEAM learned.

Why here? The Bureau of Alcohol, Tobacco, Firearms and Explosives points to our open highways with access to JaxPort. Those interstates include I-10, even I-75, and the big one, I-95.

In fact, I-95 is so notorious for gun trafficking, it's called the "Iron Pipeline." Guns from Florida and Georgia head north to be sold for big bucks in states with stricter gun laws.

And, when you add in Jacksonville's port, ATF says it makes our city a perfect place for international gun trafficking rings, bringing the criminal element to town -- along with the weapons.

The I-TEAM was given access to video and pictures detailing a 2011 closed case involving busted gun smugglers who used our highways and then hoped to use our port and the cargo ship El Faro to send their illegal stash to drug dealers in Puerto Rico. The guns never actually made it onto the ship, thanks to a Border Patrol K-9.

Surveillance video obtained by the I-TEAM shows a semitruck pulling vehicles through the gates of JaxPort. One of those vehicles on the back of that semi is a green minivan.

At first, there are no obvious signs of a crime, but the K-9 alerted agents to look further.

"This is a, 'Holy cow, that's a lot of firearms!'" said ATF Senior Special Agent Brian MacCarthy, who worked this case as it broke in 2011.

MacCarthy tells the I-TEAM he counted 64 guns: pistols, semi-automatic rifles, and high-capacity magazines -- all wrapped in plastic and hidden deep inside the green minivan. Agents carefully removed the bagged firearms from behind paneling of the vehicle.

"It's my largest case to date in Jacksonville," MacCarthy said.

He says there were 52 Glock pistols hidden in the tailgate alone. Other guns were shoved in the side panels, hidden by a stereo system.

"These things are going to sell for three times what they sell for in the United States," MacCarthy said.

He says to buy used, the cost is about $450 per firearm at a gun show. However, the street value in Puerto Rico was $1,500-1,800 per gun.

So this bust by ATF was worth more than $100,000 -- confiscated at JaxPort before they could get to the drug traffickers in Puerto Rico.

On the day these guns were confiscated, May 20, 2011, MacCarthy had what was left of the minivan and 64 weapons.

PHOTOS: ATF images of gun-smuggling bust at JaxPort

The next thing he needed to do was find the bad guys behind the smuggling operation.

The following four months involved undercover stings at the port in Puerto Rico, along with stings at Orlando International Airport.

ATF's investigation led agents to a tangled web of criminals working out of Orlando and Live Oak.

Agents made their arrests and, in the process, were able to confiscate even more illegal guns.

PHOTOS: ATF images of investigation to find gun smugglers

Investigators also uncovered the origin of most of the guns confiscated at JaxPort. Agents tell us nearly all of those guns were once legitimate law enforcement firearms -- all turned in properly -- only to later be obtained by dirty gun dealers and then sold on the black market for big bucks.

"When guns are trafficked through Jacksonville, does that put Jacksonville at a greater risk for crime?" the I-TEAM asked MacCarthy.

"Absolutely," he responded. "We know bad folks, criminals, convicted felons, illegal aliens -- people who want to utilize firearms -- if they can get their hands on firearms, they will do so."

ATF Assistant Special Agent in Charge Trevor Velinor -- the same agent who traced the guns used in the Pulse nightclub mass shooting in June -- tells the I-TEAM that Jacksonville's interstates do increase our risk.

"You have a very transient type situation where there are byways and crossways for folks to travel from Florida to Georgia and other locations," Velinor said. "So there are folks who in fact are going to get their hands on firearms."

"These things have to go through somewhere, like a funnel," added MacCarthy.

New ATF numbers obtained by the I-TEAM show Jacksonville has the most crime guns recovered for the entire state for two years in a row.

Out of the 19,000 crime guns in Florida in 2015, 2,025 of them were recovered in Jacksonville. In 2014, another 19,000 crime guns were found in Florida -- with 1,917 of those in Jacksonville. Again, the most statewide. (See interactive graphic of firearms recovered in Florida last year at the bottom of this story.)

"There are a lot of people coming to Florida to acquire guns," MacCarthy said.

He adds, the reason is simple, "They're relatively cheap."

In the wrong hands, those guns can be dangerous and profitable. Recently, four New York City police officers were killed in the line of duty, with guns that arrived via that "Iron Pipeline."

Unfortunately, Agent MacCarthy says there isn't a way to ever estimate how many guns are on the streets of Jacksonville because there are guns that are utilized in crimes that aren't recovered.

"There are individuals that possess firearms that should not be in possession of firearms, so therefore, they'll conceal those firearms," he said. "What we can do is we can make our best effort to investigate firearms related incidents."

The ATF Jacksonville office tells the I-TEAM this case was one of the most complex to unravel.

Although the case happened in 2011, agents haven't been allowed to talk about it until now -- after the successful prosecution of two suspects, whose appeals expired. A federal judge sentenced one to two years in prison, the other to a three-year prison term. Both have since been released.

It's important to note, ATF says for their 2011 gun-smuggling case, the El Faro crew was very helpful in their investigation.

The I-TEAM asked if other guns were smuggled the same way before this particular ring was busted. Agents say they can't say for sure, but they do know the same suspects did get two other vehicles through JaxPort and onto cargo ships operated at the time by the Sea Star Line, which is now TOTE Maritime.