In 2004 Marvin Heemeyer went to extreme lengths to exact his revenge upon those he felt had wronged him.

In 2004 Marvin Heemeyer, an owner of a muffler shop, set out on a mission of vengeance. Following a dispute with the authorities in the town of Granby, Colorado, he was left furious. And so, in response, he got to work creating a vehicle with terrifyingly destructive capabilities.

Born in South Dakota in October 1951, Heemeyer moved to Granby in around 1994, according to a neighbor. And several of those closest to him said he was a seemingly pleasant fellow. His sibling, Ken, even claimed to The Denver Post in 2004 that Heemeyer would have “[bent] over backwards for anyone.”

Heemeyer had also gained a reputation around Granby for his ability to modify snowmobiles. Apparently, he was the owner of the quickest such vehicle in the whole town. He also came to be referred to locally as “Marv the Muffler Man,” in reference to the TV advertisements he did for his muffler store.

According to Heemeyer’s friend Pete Mitchell, the former had been quite an adept welder. Mitchell told The Denver Channel in 2004, “He could change a muffler by himself in 20 minutes. No wasted motion. He knew what he was doing.”

But aside from his obvious talents, Heemeyer also exhibited a darker side. In fact, Christie Baker, a local resident, once spoke out about just that very aspect of his personality. Only a few days after Heemeyer had made the headlines in 2004, Baker spoke to The Denver Post about a particular experience she’d had.

Baker claimed that her spouse, Doug, had gone to Heemeyer’s place of work to get a muffler installed onto his vehicle. However, he’d been unhappy with the work done, and had declined to cough up any money. From this point, Baker alleged, Heemeyer then started to act menacingly towards her partner.

“[Heemeyer] has threatened my husband’s life,” Baker told The Denver Post. “He threatened my husband over a muffler.” And eventually, she and her husband relented, later coughing up $124 for Heeymeyer’s service, with the money going through a third party.

So it seems that if we are to believe Christie Baker’s claim, Heemeyer was not a character to be crossed. And his patience would be tested once again, this time with the local authorities. But on this occasion, the sheer lengths that he went to in order to exact revenge were quite astonishing.

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Heemeyer’s feud with the Granby town council emerged as the result of a proposal to build a concrete plant within the vicinity of his muffler store. Heemeyer was opposed to this idea on the grounds that the construction would block access to his shop. And when his objections to the project were ignored, he slipped into a bitter rage.

Furious with the local council’s plans, Heemeyer then started to hatch a rather deranged plan. Getting hold of a Komatsu D355A bulldozer, the incensed man began to deck the vehicle out with metal armor. And he also installed a number of cameras to the bulldozer’s exterior. This meant that a picture of its surroundings would be fed inside to the driver.

Heemeyer apparently thought ahead to his planned revenge mission enough to reason that the visibility offered by his cameras might become compromised. So, with this in mind, he outfitted his bulldozer with air containers capable of blowing particles away from the lenses. He also set up air conditioning inside the cabin.

The metal armor was installed so as to protect the actual body of the bulldozer, as well as its engine and a little of its tracks. And this protective shield was a foot thick in certain sections, meaning that the vehicle could withstand gun fire and explosions.

And on top of all these already elaborate modifications, Heemeyer fashioned some holes in the sides of the bulldozer. These gaps would allow him to poke a weapon outside and fire it while being protected by the metal armor of the vehicle.

Heemeyer busied himself with modifying the bulldozer for an extensive period, and notes written at the time expressed his surprise that the authorities hadn’t acted. He wrote, “It’s interesting how I never got caught. This was a part-time project over a one-and-a-half-year time period.”

In his notes, Heemeyer also recalled an occasion when three men paid him a visit. But despite the equipment and work on the bulldozer being visible, they hadn’t notice it. He continued, “Somehow their vision was clouded.”

Eventually, Heemeyer’s so-called “Killdozer” had been completed. The name for his vehicle was borrowed from a story by the American author Theodore Sturgeon. Killdozer! was actually a science fiction novella first published in Astounding magazine in 1944.

Heemeyer’s Killdozer, for its part, was quite the feat of engineering. So much so, in fact, that even local Granby officials couldn’t help but sound in some way impressed by its creator’s knowhow. Grand County Commissioner James Newberry told The Denver Channel, “How he built this was amazing. This was a very intelligent man. Once you saw the way his workshop was set up it’s possible [he did it on his own].”

Heemeyer’s completed vehicle, however, seemingly left no room for his escape. And when the time came to position himself inside the Killdozer, it would ultimately prove difficult for him to emerge again. As one official named Duane Dailey told the Associated Press at the time, “Once he tipped that lid shut, he knew he wasn’t getting out.”

By June 4, 2004, Heemeyer was ready to wreak havoc upon the town that he felt had wronged him. So, he hopped inside his heavily clad bulldozer, secure inside and ready to commit a truly atrocious crime. He was about to set out on a deranged, yet meticulously planned rampage.

Heemeyer’s path of destruction was intended to impact specific figures and institutions that he felt had mistreated him. For instance, throughout the course of his attack, he aimed his Killdozer in the direction of the town hall. And he also managed to take out the residence of the town’s past mayor.

Elsewhere, Heemeyer sent his vehicle barreling through the concrete plant at the heart of his dispute with town officials. He also slammed into the premises of a local newspaper that had previously written in opposition to him. Plus, he smashed into another person’s business, seemingly to fulfill a personal vendetta.

Witnesses to the rampage later expressed their shock at the terrifying events that had unfolded before their eyes. One man named Rod Moore had looked on as the Killdozer rolled very near past his business. As he put it to NBC News in the wake of the turmoil, “It looked like a futuristic tank.”

Apparently, the Killdozer – while it was in the process of taking out posts, trees, homes and businesses – soon became surrounded by armed cops, who were walking alongside the vehicle helplessly as the destruction continued. And as they yelled for the people of the town to retreat from the scene, they apparently fired their weapons into the vehicle.

One particular cop, called Trainor, managed to position himself on the roof of the Killdozer. And there, he fired a number of rounds into the top of the vehicle, but his efforts came to nothing. Local man Rod Moore saw all of this occur, later describing the dramatic scene to NBC News.

“[Trainor] just kept shooting,” Moore told the news outlet. “The dozer was still going. He threw what looked like a flash-bang down the exhaust. It didn’t do a thing.” A flash-bang – also known as a stun grenade – is a gizmo which blows up with a loud noise and an intense burst of light.

For her part, local woman Sandra Tucker watched the Killdozer set out on its path of destruction while she was in the middle of her working day. She told NBC News, “Gunfire was just ringing out everywhere. It sounded to me like an automatic rifle, firing about every second.”

As we’ve seen, law enforcement’s attempts to neutralize the Killdozer were proving to be ineffective. Even a SWAT team which had been sent to the scene was making little headway – the vehicle’s armor plating was doing its job. Even efforts to destroy the cameras feeding Heemeyer a view of his surroundings came to nothing, thanks to the three-inch bulletproof plastic protecting them.

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With police and SWAT firepower having little to no impact, the governor of Colorado Bill Owens allegedly contemplated taking drastic action, according to author Ron Franscell. Apparently, he considered allowing the National Guard to take the Killdozer out with an Apache helicopter using either a Hellfire or Javelin anti-tank missile.

However, those that worked with the governor at the time consistently denied that such a plan was ever considered in the years that followed. Nevertheless, State Patrol members alleged that Owens really did weigh up this option, but opted against it over fears of collateral damage.

Thankfully though, the need to undertake such a dangerous attack from the air was eventually alleviated. Because as Heemeyer tried to demolish the Gambles hardware store, he managed to get his Killdozer stuck. One of its tracks had become lodged in the basement of the store, impairing the vehicle.

Mercifully, the Killdozer was finally unable to move and carry on its path of destruction. So, after more than two terrifying hours of extensive damage being inflicted upon Granby, Heemeyer’s rampage was over.

According to reports, around a minute after the Killdozer had become stuck, a member of the SWAT team near the vehicle heard a single loud bang come from inside. Later on, it became clear as to what that sound had been. Using a .357-caliber gun he had taken with him on his spree, Heemeyer had taken his own life.

Image: via Laura Moss / EyeEm/Getty Images

Yet even now that the vehicle had come to a stop, the police still struggled to penetrate its armor, even after using explosives on three occasions. Eventually, law enforcement had to use an oxyacetylene cutting torch to get through. And finally, at 2:00 a.m. on June 5, the deceased Heemeyer was taken out of the cabin.

Reports published in the immediate aftermath of the rampage estimated the damage inflicted to be as high as $4 million, 7NEWS reported. After all, Heemeyer’s Killdozer had totally demolished eight buildings, while also damaging another five.

The hardware business owner whose building was destroyed told The Denver Channel that it would cost around $500,000 to repair the premises. And elsewhere, repairs to Granby’s library and the town hall were estimated to be around $1 million. And the Liberty Bank building, which had recently been constructed for around $1.3 million, was also left in a bad state.

But Heemeyer’s trail of destruction didn’t end there, because former mayor L.R “Dick” Thompson’s home had endured the wrath of the Killdozer too. And even though Thompson himself had passed away a number of years prior to the rampage, the Killdozer driver had seemingly retained his anger.

Following Heemeyer’s destructive spree, some of the people of Granby started to reflect on the man himself. Sheriff Rod Johnson told the Associated Press at the time, “I guess he was a lot more deranged than I ever thought. I’ve had conversations with him, and I never thought he was this obsessed with this.”

Recordings that Heemeyer himself created before his rampage have shed further light on what was going on inside his mind. These tapes were sent by Heemeyer to his sibling, who then ensured that the FBI received them. In total, around two-and-a-half-hours-worth of audio content was created.

“I think God will bless me to get the machine done, to drive it, to do the stuff that I have to do,” Heemeyer said at one point in the recording. “God blessed me in advance for the task that I am about to undertake. It is my duty. God has asked me to do this. It’s a cross that I am going to carry and I’m carrying it in God’s name.”

In the 15 years since Heemeyer’s Killdozer rampage, the man and his crime have captured many people’s imaginations. In fact, a documentary recounting that fateful day entitled Tread was even released in March 2019. And given the elaborate lengths that Heemeyer went to exact his revenge over such a comparatively trivial issue, it should really come as no surprise that his actions have aroused such dedicated interest.