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The Killdozer: Marvin Heemeyer’s Homemade Vengeance Weapon

Mamerto Adan is a feature writer who is back in college once again. Science is one of his favorite topics.

Marvin Heemeyer's "Killdozer"

Marvin Heemeyer's "Killdozer"

Frustration Sends Man Over the Edge

Yes, I know, dealing with government officials is a real pain most of the time. Ironically, we are the ones paying their salaries with our hard-earned tax money, yet it’s them who are giving us a hard time. Having worked in a government office before, I admit firsthand that people got all the reasons to complain about the services they are getting. And you might agree that a law must be passed that will allow commoners to fire their public servants. At some point, I was wondering if they are more liabilities than help.

A man going by the name Marvin Heemeyer was having the same dilemma about his local council officials. He was running a small business until the council crossed paths with him, although there were words that he was not an innocent victim and greed played a part. It was hard to tell if his reasons were noble or not, or if he was truly driven by the local government’s injustice. But he then decided to take matters into his own hands, and he spent months turning a bulldozer into a hulking armored vengeance weapon dubbed the “Killdozer.”

Marvin Heemeyer inside his modified bulldozer

Marvin Heemeyer inside his modified bulldozer

Who Was Marvin Heemeyer?

It all began with a man named Marvin John Heemeyer, a typical American blue-collar fellow. He lived in Grand Lake, Colorado, but he moved to town 10 years before the incident, according to his neighbor. He was described as good-natured, though he threatened a man for refusing to pay for a muffler repair. And speaking of muffler repair, he bought land for $42,000 and opened a muffler repair business shop. He was living a peaceful life until he ran afoul with government officials for a zoning dispute.

There are conflicting sides to his stories, but after ten years of operating his small business, the construction of a massive concrete plant was approved at the edge of his property. The problem here was that the construction would block access to his business, a serious issue for Heemeyer as customers would have trouble reaching his shop. According to some accounts, Heemeyer appealed to the town’s zoning commissions, but he was denied, and things began to worsen for him. Soon he got a series of fines amounting to $2,500 dollars, which included violations of city health ordinances for not having a proper septic tank. But some accounts stated that the dispute was not about small business oppression, but due to greed.

Others stated that Heemeyer proposed to sell his land to the company that owned the concrete plant. His choice of price was $250,000 for his two-acre land, which soon increased to $375,000. Eventually, the selling price reached a million dollars, and some believed that the company simply stopped dealing with Heemeyer and just pursued their zoning rights. However, there are others who reckoned that the negotiation happened before the rezoning proposal.

Whatever side of the story one believes, Heemeyer saw this move as unjust. And for 18 months, he was secretly plotting his revenge in a form of a modified bulldozer.

Heemeyer's armored bulldozer

Heemeyer's armored bulldozer

The Killdozer

He first leased his business to a different company before selling his property to a third party. The money was used to customize a bulldozer into a form of improvised armored fighting vehicle. It started with a Komatsu D355A bulldozer, fitted with makeshift armor of concrete sandwiched between steel plates. The armor could be as thick as one foot, and it covered the cabin, the engine, and parts of the tracks. Yet the armor completely covered the window of the cabin, but Heemeyer installed cameras linked to a monitor on his dashboard for visibility. The cameras were protected by a clear bulletproof Lexan shield. Air jets were added to blow dust off the camera.

The interior of this makeshift tank was airconditioned, and guns peered out from gun ports. There were three of them: a .50 caliber rifle, a .308 semiautomatic rifle, and a .22 LR rifle.

Yet with all these complexities, the modified bulldozer which he called the “MK Tank” was a virtual suicide weapon. Authorities believed that Heemeyer used an improvised crane to lower the whole armor shell on the bulldozer, and he did this while he was inside the cabin. There was no means of getting out and he basically sealed himself in his vehicle. He had no intention of getting out, and he expects to go down after he completed his vengeance mission.

It took Heemeyer 18 months to construct his monster, and he boasted in his note how he was never caught despite how several men visited his shed. And after he killed himself and his vehicle was captured, it earned the name “Killdozer” after the short story by Theodor Sturgeon.

The Killdozer rampages through town

The Killdozer rampages through town

The Rampage

And on June 4, 2004, off he went with his Killdozer for a rampage. He first started on the walls of his former business before plowing his way through the concrete plant. He then drove the beast into the town and demolished the Town Hall. The office of the local newspaper critical to his zoning dispute went down next, and the house of the former mayor who was involved in the dispute wasn’t spared either.

A total of thirteen buildings felt the wrath of Heemeyer in his Killdozer. The rampaging monster also claimed a natural gas service connected to the town hall and concrete plant, a truck and a part of the utility service center. The damage amounted to seven million dollars, but amazingly no one was killed during the rampage.

And the sheriff’s department could not do anything to stop the raging monster.

Cody Docheff tried to stop the assault on the concrete plant with a wheel-tractor scraper, but the heavy equipment was merely pushed aside by the armored bulldozer. Worst, Heemeyer fired multiple shots at him with his semi-automatic rifle from the firing port. The SWAT team was brought in and one officer dropped a flashbang grenade down the exhaust pipe. But it had no effect. The same could be said for the shots fired by the SWAT at the composite armor of steel and cement. They tried various approaches, like disabling the bulldozer’s camera with gunfire. This ended in failure as the bullets could not penetrate the clear Lexan shield. The undersheriff Glenn Trainor even tried to play action hero by climbing at the back of the bulldozer to find a way to get a bullet inside. But the threat of debris forced him to jump off. Governor Bill Owens considered bringing in an Apache Gunship from the National Guard, or a team with anti-tank missile to destroy the bulldozer. The plan was scrapped due to the risk of even greater collateral damage.

Eventually, the Killdozer was damaged when Heemeyer attempted to destroy the Gambles hardware store. After the engine failed, Heemeyer shot himself with a .357-caliber handgun.


During the rampage, only Heemeyer was killed and people claimed that he went out of his way to not harm anyone. The sheriff’s department attributed this more to sheer luck and not to Heemeyer’s good intentions.

It took hours for the police to remove Heemeyer’s body from his bulldozer. Explosives failed to open the armor shell, and they resorted to oxyacetylene to cut through the steel. The bulldozer was eventually scrapped, and the pieces dispersed to avoid souvenir taking.


1. Best, Allen (July 2004). "The Dark Side of the Paradise," Colorado Central Magazine.

2. Ingold, John; Brittany Anas; Howard Pankratz (June 6, 2004). "'Something snapped': Suspect called emotional, angry over rezoning fight." The Denver Post.

3. Hollings, Alex (March 18, 2019), "Folk Hero or Real Villain? The Complex Tale of Colorado's 'Killdozer."

This content reflects the personal opinions of the author. It is accurate and true to the best of the author’s knowledge and should not be substituted for impartial fact or advice in legal, political, or personal matters.