Wisconsin’s Most Wanted FBI Target is a 76-Year-Old Domestic Terrorist

For more than five decades, one of Wisconsin’s most notorious fugitives and domestic terrorists has managed to evade capture. Linked to a deadly bombing that shook the University of Wisconsin–Madison in 1970, this indicted criminal remains on the FBI’s most wanted list to this day. Despite relentless searches and newly released age-progressed images from the FBI, he has never been found.

The crime in question is the Sterling Hall bombing, which occurred on August 24th, 1970. A group of four anti-war radicals set off a massive explosive in an attempt to destroy the Army Mathematics Research Center, or AMRC. The AMRC was targeted as it was an army funded think tank. A newspaper at the time published a series of investigative articles making a convincing case that AMRC was pursuing research that was directly tied to specific U.S. Department of Defense requests, specifically relevant to counterinsurgency operations in Vietnam.

The bomb that was used in the attack consisted of nearly 2,000 pounds of ammonium nitrate and fuel oil. It was loaded into a Ford Econoline which had been stolen from a UW-M professor of computer sciences. It decimated Sterling Hall and damaged an additional 26 surrounding buildings, however the AMRC itself was only slightly affected. The explosion was so powerful that pieces of the van were found on top of an eight-story building three blocks away.

The blast claimed the life of 33-year-old physics researcher Robert Fassnacht, who had no ties to the military, and injured three others. It also caused an estimated $6 million in damage to the building and its contents. The bombing also led to Department of Defense phasing out the AMRC by the end of the 1970 fiscal year.

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The perpetrators of the attack, Karleton Armstrong, Dwight Armstrong, David Fine, and Leo Frederick Burt, were said by eyewitnesses to flee in a light-colored, late-model Corvair. At the time, David Fine and Leo Burt were students at UW–Madison and writers for the campus newspaper, The Daily Cardinal. They both became involved in radical anti-war activism led by Karleton, along with his younger brother, and played a key role in the attack.

This wasn't even their first attempt at terrorism. The group, dubbed the "New Years Gang," stole a small plane from Morey Field in Middleton on New Year's Eve 1969. Using it, they attempted to drop homemade explosives on the Badger Army Ammunition Plant, but the explosives never detonated. They then managed to land the plane at another airport and escaped.

All in all, three of the four men were arrested and charged. Karleton Armstrong served just 7 years of a 23-year sentence. Dwight Armstrong, Karleton's younger brother, was sentenced to seven years, but served just 3. He was then arrested again and sentenced for 10 more years for distributing amphetamines. David Fine was also sentenced to 7 years but served just 3. Leo Fredrick Burt, on the other hand, was never caught after the group escaped together to Canada initially.

Over the years, authorities have followed numerous leads, but none have led to Burt’s arrest. The FBI continues to update his profile, releasing digitally aged images to help the public identify him. The most recent images, unveiled in 2023, depict what he might look like today, at around 75 years old.

The Sterling Hall bombing was the deadliest act of domestic terrorism in the U.S. before the Oklahoma City bombing in 1995. Despite the passage of time, the FBI has not given up its search for Burt and is still offering a $150,000 reward for information leading to his capture. Anyone with information is encouraged to contact the FBI’s Milwaukee Field Office or submit a tip online.