FILE - This undated file photo provided by the North Dakota Statewide Automated Victim Information and Notification Program shows Chad Isaak. Jurors returned guilty verdicts Friday, Aug. 20, 2021 on all counts against Isaak, who was charged in the deaths of RJR Maintenance & Management co-owner Robert Fakler and employees Adam Fuehrer, William Cobb and Lois Cobb in April 2019. (North Dakota Statewide Automated Victim Information and Notification Program via AP, File)

BISMARCK, N.D. (AP) — A jury found a chiropractor and Navy veteran guilty Friday in the gruesome killings of four people at a North Dakota property management firm two years ago.

Jurors returned guilty verdicts on all counts against Chad Isaak, who was charged in the April 1, 2019, deaths of RJR Maintenance & Management co-owner Robert Fakler, 52, and employees Adam Fuehrer, 42, Bill Cobb, 50, and 45-year-old Lois Cobb. The Cobbs were married.

Isaak 47, of Washburn, whose mobile home was on property managed by RJR, pleaded not guilty to four counts of murder and three other counts. He faces a maximum sentence of life in prison without parole.

Isaak, in handcuffs, looked down before the verdicts were read but showed little emotion as the jury’s decision on each count was announced.

A jury of six men and six women deliberated four and a-half hours before finding Isaak guilty following the three-week trial.

It was one of the most heinous crimes in North Dakota history, defense attorney Bruce Quick acknowledged in his opening statement. Three of the victims were shot and stabbed at the business in Mandan, a city of about 20,000. Combined, the four of them were stabbed about 100 times.

Judge David Reich did not immediately schedule a date for sentencing.

Quick said during the trial that the case amounted to a rush to judgment based on bad information that led to the wrong conclusion. The defense rested its case Wednesday.

Prosecutor Karlei Neufeld described the horrific crime scene during the trial and said evidence that included photos, surveillance video, bullet fragments, a knife and other items found during searches of Isaak’s home and vehicle led to the charges against him.

Prosecutors presented the case as a puzzle in which all of the pieces pointed to Isaak, including a knife found in his clothes washer, gun parts found in his freezer and security camera footage tracking his pickup.

BCI Supervisory Special Agent Arnie Rummel testified that investigators were not able to determine a motive, but that a motive isn’t a requirement for conviction.

The defense maintained that authorities overlooked numerous possible alternative suspects. Isaak’s attorneys also questioned the sourcing, collection and processing of evidence; said some testimony doesn’t match police reports; and questioned the absence of visible blood on the clothing of a person seen in security camera footage leaving RJR the morning of the killings.

Prosecutors showed security camera footage from numerous businesses that authorities said tracked Isaak’s white pickup from Mandan to Washburn on the day of the slayings, along with footage from a week earlier that they said indicated the killer planned out the attack.

Forensic experts testified that fibers on the clothing of the slain workers were matches for fibers taken from Isaak’s clothing, and that DNA evidence found in Isaak’s pickup truck was linked to Fakler and possibly Lois Cobb.

News from © The Associated Press, 2021