After Bucks killing, coworkers and friends remember Michael Mohn for the way he lived: ‘Whatever was needed, he was there’

When U.S. Army Corps crews drilled deep into the contaminants of South Jersey’s Lipari Landfill — at one time a top Superfund site in the nation — it was Michael Mohn who volunteered to put himself at risk, donning a hazmat suit and oxygen mask to test potentially hazardous samples.

That’s just who Mohn was, said his friend and former colleague Dan Sirkis.

“Mike would do anything. Whatever was needed, he was there,” said Sirkis, chief of the U.S. Army Corps of Civil Engineers geo-environmental section.

A quiet, inquisitive, and easygoing man who often shied away from the spotlight, Mohn made national headlines last week after officials say he was murdered — fatally shot, then decapitated by his son in their Levittown home. Justin Mohn, 32, then went on to post a graphic YouTube video about the killing, authorities say, calling for the torture and execution of federal workers. He has been charged in Bucks County with first-degree murder, abuse of a corpse, and possessing an instrument of crime, and is being held without bail.

But following his killing, Michael Mohn’s friends and coworkers say they hope to remember him for the way he lived: as a thoughtful, innovative civil engineer dedicated to creating a cleaner environment, and someone who cared deeply about his wife, two sons, and daughter.

“He did everything he could for his family,” Sirkis said, adding that Mohn and his wife “were just selfless, devoted parents.”

News of the federal engineer’s violent death rocked the Levittown-area community, said Sirkis, who lives in nearby Morrisville. “It’s palpable,” he said.

Neighbors left flowers and a small cross outside the Mohns’ home. “Our whole community mourns and aches over this,” Middletown Township Police Chief Joseph Bartorilla said during a news conference last week.

“They didn’t all know Mike, but they were shocked that it happened to somebody here. And my neighbors, all of them said the same thing,” Sirkis said. “It’s just been a very difficult thing.”

Remembered by his coworkers for his wry sense of humor, endless curiosity, and warm greetings, Mohn, 68, meticulously planned for a peaceful retirement and carefully studied stock trading, said his longtime colleague and friend Vinny Grassi. He retired from the Corps in 2022 after two decades, and came back shortly after to work part time.

“He always used to say, ‘You plan the work, then you work the plan,’” Grassi said.

He took pride in his children’s successes, his colleagues said, and was quick to offer a helping hand, research, or a science textbook. He exuded the values of the Army, Sirkis said, but above all, “selfless service.”

At the Army Corps’ Center City offices, he arrived early to work, and was always quick with a joke, coworkers said.

“Sometimes in the government, you could get kind of bogged down with the minutiae,” said Joe Loeper, who worked alongside Mohn for 12 years. “He took his work seriously and got the job done, but always saw the light side.”

“Everything he did had a purpose,” Sirkis said. “All the projects he worked on were in the Philadelphia area to do something better for our environment, to keep chemicals from getting into the river, to help remove radioactive and carcinogenic chemicals and metals from the soil so that future generations don’t have to deal with that.”

In helping crews to clean a large gas spill in Pennsylvania, Mohn devised a way to safely recover gas lodged in an underground mine, drilling into a backyard without risk of explosion, Sirkis said. One of Mohn’s last jobs before his death involved upgrading a South Jersey plant responsible for removing radioactive soil leftover from the Manhattan Project. A contractor there held a moment of silence Monday in Mohn’s memory, Sirkis said.

“Everything he did impacted people in some way that live in the Delaware Valley,” Sirkis said.

In his spare time, Mohn played guitar, rocked out to heavy metal, cheered on the Philadelphia Flyers and Eagles, and played ice hockey until he was in his 50s. He grew up in the Levittown area, and was interested in chemistry from a young age, collecting and inspecting fireworks as a child. He would recount to colleagues his introduction to the thermite reaction: the time some firework powder exploded in his childhood bedroom, accidentally burning a mark on the wooden floor.

Mohn studied chemistry in college, and later earned his master’s degree in civil engineering. In 2001, after having worked for years as a private environmental firm where he held five patents, he began with the U.S. Army Corps, first as a chemist, and later as an engineer with expertise in wastewater treatment processes. In 2019, he was presented with the Philadelphia District’s highest employee honors for outstanding achievement — a recognition that “meant a lot to him,” Sirkis said.

In a statement, the district called Mohn a “gifted innovator, a consummate professional, an invaluable mentor, and a dear friend.”

“We miss him already and he will always hold a place in our hearts.”

Staff writer Ximena Conde contributed to this article.