After four and a half hours of deliberation over two days, a jury Friday has found Washburn resident and chiropractor Chad Isaak guilty of the murders of four people at RJR Maintenance and Management in Mandan on April 1, 2019.

Isaak was also found guilty of burglary for unlawfully entering the RJR building while it was closed to the public, guilty of unlawful entry into William Cobb’s RJR vehicle and unauthorized use of the RJR vehicle, which was driven to Indigo Signs shortly after the killings at RJR.

The jury began deliberating the case around 2:00 p.m., Thursday, and broke for the evening three hours later. The six men and six women then resumed deliberations Friday morning at 8:30 a.m. and came back with the verdict at about 9:45 a.m.

Chad Isaak during the reading of the verdicts Friday

Judge David Reich ordered a pre-sentence investigation and an opportunity for victim impact statements, if desired. A sentencing date has yet to be set.

The 15-day trial at the Morton County Courthouse was notable for the lack of a motive in the killings, a large amount of circumstantial and video evidence, and a reliance on forensic analysis of orange fibers and DNA samples.

RJR co-owner Robert Fakler and employees William Cobb, Lois Cobb, and Adam Frueher were brutally killed in the shop and front office of the RJR building in Mandan in the early morning hours of April 1, 2019.

Using video surveillance footage from RJR and surrounding businesses, investigators were able to generate a description and images of the suspect and a suspect vehicle, a white Ford F-150 pickup.

From the videos, authorities testified they were able to track the suspect vehicle from a McDonald’s parking lot along Memorial Highway in Mandan to the Missouri River bridge crossing in Washburn.

The distinctive rust formation on the rear wheel well of the suspect truck, coupled with other unique mud marks on the front bumper, the black trim with no liner on the pickup bed, and other identifying marks caught the attention of McLean County Sheriff’s Office Lieutenant Justin Krohmer in “Be On The Lookout” (BOLO) bulletins sent to law enforcement on April 3 and April 4 of 2019.

Krohmer, who lives in Washburn, was an occasional patient of Chad Isaak, and Krohmer knew Isaak drove a white F-150 with very similar characteristics to the ones shown in the BOLO bulletins.

On April 4, 2019, authorities stopped Isaak as he drove in Washburn and executed search warrants of his person, his truck, his home, and his downtown chiropractic business.

Among the pieces of evidence seized: Parts of a firearm in a plastic container inside the refrigerator freezer in Isaak’s home, an orange hoodie, a reversible face mask, black pants and black shoes in Isaak’s dryer similar to the clothing worn by the suspect in the videos; a knife with a bent tip in Isaak’s washing machine underneath some wet clothing; nine shell casings in a sock in one of Isaak’s home closets; dark gloves and other clothing very similar to those worn by the suspect in the videos. Some investigators also mentioned the smell of bleach when they entered Isaak’s home.

Investigators also found 16 pairs of size 12 Avia dark shoes at Isaak’s business that were similar to those worn by the suspect in the videos and as well as a business appointment book with morning appointments scheduled for April 1, 2019, that were moved to later times and dates. Isaak told one of the patients he had rescheduled that he had a dental appointment that morning, but authorities said they could not find evidence that Isaak ever went to a dental office that day.

In addition to the video from April 1, an employee of Big O Tires in Mandan noticed something familiar about the suspect’s movement in his business’ surveillance videos. When he reviewed video from March 25, exactly a week earlier, he found the same similarly dressed suspect going through the same motions as on April 1.

When authorities matched surveillance video from Memorial Highway businesses for April 1 and March 25, 2019, at the same time as the murder, they found the videos “eerily similar,” as one investigator put it, in the time the white Ford F-150 arrived and parked at McDonald’s, the clothing the suspect was wearing, the paths he walked to and from RJR and the direction the white Ford F-150 followed leaving the McDonald’s parking lot. One investigator testified the timing of both videos was within 30 seconds of each other for much of the movements, suggesting the suspect was rehearsing his plans for the following week.

Chad Isaak was formally arrested on April 4, 2019.

During Isaak’s trial, the prosecution took pains to methodically lay out the evidence, putting together a video timeline from various business surveillance videos showing the suspect and the victims arriving at RJR, the suspect leaving RJR and apparently driving William Cobb’s RJR truck to Indigo Signs, the suspect walking back to his truck parked at McDonald’s and the truck’s journey along Memorial Highway to west on Main Street in Mandan, north on Highway 25 past the Flying J truck center and then along Highway 200 into Washburn across the Missouri River.

The prosecution also laid out a forensic evaluation of Isaak’s shoes from his dryer and a shoeprint found at the scene of the murders, with an analyst saying the print could have come from the same class of shoe, but couldn’t say they matched conclusively.

Lots of DNA evidence was also introduced by the prosecution with two bits of evidence swabbed inside Isaak’s truck showing DNA from Isaak, and parts of DNA that could not exclude Robert Fakler and Lois Cobb.

Orange fibers were also collected and analyzed by a forensic expert who concluded the fibers from Chad Isaak’s reversible face mask and orange hoodie matched the fibers found on the bodies of the four victims, inside William Cobb’s RJR vehicle and inside Chad Isaak’s truck.

While the physical clothing, guns, and knives and other evidence seized from Isaak’s home, truck and residence appeared to match the evidence seen in the videos and in evidence found at the RJR crime scene, it was largely circumstantial. The forensic evidence — the orange fibers and the DNA — were the elements that appeared to directly connect Isaak to the killings.

The defense vigorously contested the evidence, saying police failed to follow up on other leads that could have pointed to suspects other than Chad Isaak. They also argued authorities broke the “chain of custody” in handling evidence, and that investigators contaminated the crime scene, Isaak’s truck, and Isaak’s home by having numerous investigators walking about and possibly touching evidence without wearing protective gear, booties and gloves. The defense said it was a clear case of confirmation bias and a rush to judgment on the part of authorities once they settled on Isaak as their suspect.

In the end, the jury of six men and six women felt the preponderance of physical and forensic evidence was enough to convict Chad Isaak in the 2019 killings.