Now we know how ISIS built such an extensive network of tunnels beneath Mosul to hide and store munitions.

The terror network managed to make its own tunnel-boring machine (see photo above), a hideous but effective part of the group's arsenal.

The discovery of the ISIS machine is credited to the Iraqi Army’s 9th Division, after which Devin Morrow, a technical adviser with Conflict Armament Research, analyzed the machine.

Most days Morrow dons a bulletproof vest and ventures to the front line of Iraq's battle against ISIS to inspect the latest spoils of a grinding and bloody war.

The 30-year-old Canadian woman is tasked with analyzing seized weaponry from ISIS -- piece by piece -- and uncovering its source and pathway to the terrorist network.

Much of the illegally traded weapons are small arms but some -- like the ISIS-made tunnel machine -- demonstrate a level of sophistication never seen before by such a group, according to Morrow.

"It's quite unprecedented, the level at which ISIS is able to create its own ammunition and weaponry," Morrow told Fox News.

"We don't see this quality of production in other conflict zones," said Morrow, whose U.K.-based company traces and documents illegally diverted weapons in conflict zones like Iraq, Syria, Somalia, South Sudan, Libya and Yemen.

Once a weapon is captured from ISIS, Morrow and her team begin their investigation -- snapping photographs of the items and examining each weapon's markings and serial number.

"We don’t rely on secondary information. We spend a lot of time out in the field," she said. "It does get scary. Anything can happen at any time and it's important to remember that."

Hundreds of seized weapons are variants of the AK-47, which Morrow described as highly versatile and easily trafficked.

"They last a long time. They’re very durable," she said of the high-powered assault rifles. "Variants of the AK-47 are very widely used in the Middle East. The main producers are former Soviet countries and Russia. They have been around for decades and they're everywhere."

Some of the ISIS items discovered by Morrow are old -- including ammunition found in northern Iraq in 2014 that was made in Nazi Germany.

"It just shows you how far that ammunition can go," she said.

Other weapons and equipment are more recently produced, including those made by the terror network itself. Among such findings are ISIS-made mortars and IEDs.

Morrow and her team have also uncovered a "suicide vehicle" she referred to as the "SVBIED." ISIS fighters, she explained, are taking civilian cars and SUVs, loading them with explosives and then covering the vehicles with heavy metal plates that help them get close to the front lines.

"They’re taking these regular cars and trucks from civilian people in Mosul and doing extensive modifications on them to make them into suicide vehicles," she said.

The terror group also is using tunnel-boring machines to dig extensive tunnel systems between houses and underneath roads to confuse coalition forces, according to Morrow.

"They built that machine themselves," she said of the tunnel machine found in Hamdaniyah late last year.

The Battle of Mosul is a joint offensive by Iraqi government forces with allied militias, the Kurdistan Regional Government and international forces to retake the northern Iraqi city from the Islamic State. The offensive began in October 2016.

For Morrow, the tracking of illegal weapons is only one part – albeit a critical one – in defeating the enemy on the ground.

"Our group actively tries to document individual items. That’s the first step in decreasing the proliferation of illegal weapons," she said.

"By creating this database and by understanding corridors and trafficking among regions – where the weak parts are around the world – then we can create more robust and responsible international arms policies."

Morrow – a Western woman in Iraq in a male-dominated field – said there is no other work she would rather be doing.

"It can be trying if you’re working with a bunch of guys – it can be a little bit stressful – but I feel very well respected and no one has ever questioned my role and my experience being there," she said. "My team is incredibly supportive."

Cristina Corbin is a Fox News reporter based in New York. Follow her on Twitter @CristinaCorbin.