DNA from 2 of 4 killed at Mandan business likely found in suspect's truck

DNA analysis of blood found at the crime scene and in Chad Isaak's truck was a focus in court on Monday, which marked the beginning of the trial's third and anticipated final week.

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Chad Isaak, who is accused of killing four employees at RJR Maintenance and Management in Mandan in 2019, listens testimony in his trial at the Morton County Courthouse on Monday. Adam Willis / The Forum.
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MANDAN, N.D. — An expert witness for the prosecution in the murder trial of Chad Trolon Isaak testified Monday, Aug. 16, that investigators could not rule out that at least two victims' DNA was in a blood stain found in Isaak's truck.

On April 4, 2019, law enforcement executed a search warrant on Isaak's Ford pickup truck, where multiple swipes of blood were visible. Authorities took swabs of the blood to send to the North Dakota Crime Laboratory for DNA testing. Some blood was found on the driver's side door frame of Isaak's truck, and former state crime lab forensic biologist Kyle Splichal testified that multiple profiles, meaning DNA from multiple people, could be detected in the sample.

For one of the profiles found in the sample, the DNA of Robert Fakler, a co-owner of RJR Maintenance & Management who was stabbed 22 times on April 1, 2019, could not be excluded as a contributor.

Specifically, Fakler cannot be excluded as a contributor to the DNA sample, and that profile can only statistically match one in 482 billion people, Splichal said Monday.

Within that same sample as well, the DNA of Isaak himself and Lois Cobb, who was stabbed 48 times, had one gunshot wound and whose throat was cut on April 1, could not be excluded as a contributor to the spot of DNA found in Isaak's truck.


DNA analysis of blood found at the crime scene and in Isaak's truck was a focus in court on Monday, which marked the beginning of the trial's third and anticipated final week. Isaak has pleaded not guilty to slaying Fakler, Lois Cobb, William Cobb and Adam Fuehrer, but if convicted, he faces the possibility of life in prison without parole.

Authorities sent multiple pieces of evidence to the state crime lab for DNA analysis, including multiple objects found inside Isaak's mobile home in Washburn, North Dakota: multiple clothing items found in a dryer, a knife with a bent tip found in a washing machine, some spent bullet casings and parts of a revolver found in a container that smelled of bleach.

However, investigators could not detect any of the victims' DNA on the items. However, prosecutor Gabrielle Goter pointed out that washing or bleaching items can destroy DNA.

During cross examination, defense attorney Bruce Quick questioned North Dakota Bureau of Criminal Investigation special agent Joe Arenz about what he first learned about Isaak during the beginning days of the investigation, in an apparent attempt to establish Isaak's character.

Isaak was awarded multiple medals in the U.S. Navy before his honorable discharge, had a successful chiropractic business before he was charged with the killings, and is a father, Quick said Monday.

Throughout the trial, defense attorneys have referred to their client as "Dr. Isaak."

"Were you aware Dr. Isaak had no criminal convictions of any kind?" Quick asked Arenz, to which Arenz affirmed. Quick then asked whether Arenz knew that Isaak had a daughter as well as a successful chiropractic business. Arenz said later, however, that authorities learned Isaak did not have many close friends.

The prosecution will continue questioning witnesses on Tuesday and could rest its case by the end of the day.


Readers can reach reporter Michelle Griffith, a Report for America corps member, at

Michelle (she/her, English speaker) is a Bismarck-based journalist for The Forum of Fargo-Moorhead and Report for America, a national service organization that places journalists in local newsrooms to report on under-covered topics and communities.
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