At the close of 1922, Wood County, Wisc., was like any other rural Midwest county where people made their living off the land. Aside from a little problem with bootleggers and a controversial drainage project, Wood County was a quiet place where people worked hard and treated each other with honesty and respect. It was the last place anyone would expect to host a murder trial that would become one of the defining moments of forensic science.
The year had been a contentious one for the County Commission. The first issue Commissioner James Chapman and the board had to contend with was an attempt to curtail the rise in bootlegging activity in the county. They voted in an unpopular and draconian ordinance to punish anyone connecting with violating Prohibition laws and provided an additional $5,000 appropriation for the sheriff to enforce the law. The board was making it clear to everyone from the organized bootlegger to the farmer who ran a small still that Prohibition was the law of the land and that Wood County would brook no violation.
The drainage project, however, made the controversy over the Prohibition ordinance pale in comparison.
For years farmers and landowners had struggled with controlling the flooding of the Wisconsin River which meandered through the county. The Wisconsin, which has its head somewhere near the Wisconsin/Michigan border and flows into the Mississippi, was a major thoroughfare for the lumber industry who had dammed the river here and there to ensure a heavy flow of water as they floated their logs to the paper mills downstate. Those dams altered the natural flow of water from the northern snows, causing problems for farmers whose fields would often suffer from overflows.
In an effort to control the floodwaters, the Wood County Commissioners had approved a plan to dredge a series of drainage ditches across the county, cutting through farmland. The plan to encroach across the private property of fiercely independent farmers was unpopular enough, but when the Board decided to pay for the project and its perpetual upkeep through new taxes on the affected property owners, the complaints increased tenfold.
No one protested more than John Magnuson, a Swedish immigrant who came to Marshfield, Wisc., by way of Chicago and South Africa.
Magnuson was a 44-year-old farmer and machinist who spoke only broken English and who lived on his farm with his wife and two teenaged children. He had no use for drainage ditches on his property and even less use for new taxes, and made no secret of the fact that he was not opposed to violence to stop the project.
Once, when approached by neighbors asking him to sign a petition against the project, Magnuson told them he planned to “peck, peck, peck against the head man” of the project with his rifle.
Magnuson was the prime suspect in the summer of 1922 when a dredge working on the project exploded in a fireball near his property. The dredge was loaded with 100 gallons of gasoline and an equal amount of diesel fuel when it exploded in the middle of the night. Although TNT was being used as part of the dredging project, the explosive was housed several hundred yards away.
Few people believed that the blast was an accident but investigators were unable to prove conclusively that the dredge was sabotaged.
In the fall of that year Magnuson approached the drain commission to protest the ditch assessment he received. The discussion quickly turned ugly. Magnuson threatened a lawsuit, then claimed Chapman was accepting bribes from the firms digging the ditches. Finally, Magnuson threatened violence.
Chapman responded that he would “make it hot” if Magnuson continued to assert he was on the take, but promised to review Magnuson’s assessment.
“He certainly was earnest about the use of violence,” Chapman said he believed at the time.
Later the two men — who openly considered the other to be an enemy — met again.
“I saw Mr. Magnuson in the fall and told him the assessment was fair and it could not be changed,” Chapman said later. It was the last time the men would talk.
Winter came and work on the ditches stopped, but apparently Magnuson continued to seethe.
Two days after Christmas 1922, postal carrier Eugene Fehrenbach was delivering mail to the Thorbald Moen farm and picked up a tubular package wrapped in heavy gray paper and tied with a string resting atop the Moens’ mailbox. The package contained no return address and in a semi-illiterate hand was addressed to “J.A. Chapman, R.1 Marsfilld Wis.”
Fehrenbach assumed the package was meant for James Chapman whose address was Route 1, Marshfield. He passed the mail along to the Route 1 postman, John Heaton, who delivered it to the Chapman home, where James Tarr, Chapman’s grandson passed it along to his grandmother, Clementine, 60.
Since Christmas had just passed, the Chapmans thought the package, 12 inches long by 1.5-inches wide and 1-inch high, was a belated gift and the family gathered around as James opened it.
As James cut the third string the pipe bomb inside the package exploded with sufficient force to blow four fingers off his left hand, leaving his little finger hanging from his wrist by the skin. His left leg, on which the bomb sat, was sliced open across the thigh.
Across from him, Clementine Chapman screamed that she was hit and was dying. She staggered from the room and collapsed on a bed, mortally wounded. She had been hit in the head by wood and metal shrapnel from the bomb, but the most serious wounds were to her torso, which had borne the brunt of the explosive force.
Tarr, standing behind his grandfather, suffered minor injuries. In shock, he ran to the telephone, screaming “for God’s sake, come quick!” over and over into the party line.
By the time help arrived, James Chapman had managed to crawl to his wife, but there was nothing that could be done for her. She died in the Marshfield hospital the next day, about the time doctors were amputating what was left of Chapman’s left hand. Surgeons were unable to remove a shard of iron that had embedded itself in Chapman’s leg — he would have it there for the rest of his life, just one reminder of the attack.
The force of the explosion drove the pocket knife Chapman used to cut the strings 2 inches deep into the wood floor and investigators later counted 40 holes in the walls caused by wood and metal shards.

A Quick Chemistry Lesson
The principle behind an explosion is quite simple, regardless of the compounds that make up the explosive material: an explosion is simply a confined combustion of oxygen and carbon which combine to form carbon dioxide. In the open, this chemical reaction (when combined with heat, of course) makes fire. When confined, however, the rapidly expanding gas pushes against its container in what we call an explosion. If the container can withstand the force of the expanding gas the explosion is harmless and can be quite useful — for example in an internal combustion engine.
When the container cannot withstand the force, it can be termed “a bomb.”
The more gas that is produced compared to the remaining solid from the base chemicals determines the strength of the explosion.

It did not take experts from the U.S. Treasury Department and Postal Inspectors long to piece together the composition of the bomb that killed Clementine Chapman. It was fueled by picric acid, one of the earliest synthesized explosives, and something readily available in a farming community like Wood County. The explosion was set off by the primer portion of a shotgun shell which ignited a detonator cap. A spring-loaded trigger made from a wagon bolt that struck the primer was connected to one of the strings binding the package. The bomb itself was an brass pipe encased in a white elm “shell.” For shrapnel the bomber had used bits of brass and iron.
Although the explosion was sufficient to kill one person, critically injure a second, and give a third minor injuries (Tarr received a cut above one eye), there was enough of the gray wrapping paper left to allow investigators to study the handwriting of the sender and the presumed bomber.
Just as it didn’t take investigators long to piece together the bomb, it didn’t take long for them to decide on their prime suspect. While there was some speculation initially that the bomb came from bootleggers in the area who were unhappy with James Chapman’s crusade against the illegal stills that dotted the county, police made it clear that they wanted very much to talk to John Magnuson.
On December 29, 1922, in what was the largest funeral anyone in the area could remember, the people of Wood County buried Clementine Chapman. The mood was ugly and there were more than a few people talking about a lynching. Posses of lawmen, citizens, and newsmen who had flocked to the small city of Marshfield fanned out across the area in search of Magnuson.
Perhaps fortunately for him, Magnuson was arrested by Sheriff Walter Mueller and his undersheriff, Cliff Bluett.
On January 4, 1923, Magnuson, protesting his innocence, was bound over for trial on first degree murder charges.
The investigation and trial would turn out to be one of early forensic science’s defining moments. In an era when fingerprint evidence was just beginning to be used in the courtroom, the guilt or innocence of John Magnuson would hang on whether prosecutors in a small Wisconsin county could convince a jury to believe the testimony of forensic linguists, handwriting analysts, ballistics experts, and chemists.
Next: The Trial of John Magnuson