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Editor's note: This is Part 4 article of The Mandan Murders, season 9 of the Dakota Spotlight podcast. Go here for Part 1, and .

WASHBURN, North Dakota — In 2019, Justin Krohmer was a detective for the McLean County Sheriff's department 40 miles north of Mandan where the RJR murders took place on April 1, 2019.

When Mandan police circulated a photograph of the suspect's vehicle and asked all law enforcement to be on the lookout, Krohmer thought the white Ford F-150 pickup looked familiar.
It looked a lot like the local chiropractor's truck. Krohmer was himself a patient there. And so were his parents, Wade and Susan.

On the early morning of April 4, three days after the murders, Krohmer quietly walked into the neighborhood where Isaak lived and snapped a couple of photographs.

Back at the sheriff's office, they compared photos.

Minutes later, dozens of law enforcement officers were headed to Washburn. The mission: Detain chiropractor Chad Isaak.

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1/12: Chad Isaak was apprehended for questioning and then arrested on April 4, 2019 for the murders of four RJR employees in Mandan. Contributed / Mandan Police Dept

2/12: Chad Isaak was apprehended for questioning and then arrested on April 4, 2019 for the murders of four RJR employees in Mandan. Contributed / Mandan Police Dept

3/12: Chad Isaak was apprehended for questioning and then arrested on April 4, 2019 for the murders of four RJR employees in Mandan. Contributed / Mandan Police Dept

4/12: Chad Isaak was apprehended for questioning and then arrested on April 4, 2019 for the murders of four RJR employees in Mandan. Contributed / Mandan Police Dept

5/12: Security video footage in Center, North Dakota captured the suspect traveling north. Contributed / Mandan Police Dept

6/12: Despite incredible evidence against him, Chad Isaak never admitted to anything nor acknowledged his guilt. At his sentencing he stated that the only thing he wanted to say was that he was not a murderer. WDAY TV

7/12: State's evidence photo in the trial of Chad Isaak connecting fibers between the sweatshirt found in Chad Isaak's home those found on the victims WDAY TV

8/12: When they searched his home, investigators found a knife in his washing machine. WDAY TV

9/12: The victims of the RJR homicides were stabbed and shot. Investigators found a knife in Chad Isaak's washing machine as well as ammunition. They also found empty shell casings seemingly hidden in a sock. WDAY TV

10/12: When they searched Chad Isaak's home on April 4, 2019 investigators found several items in his washing machine: A reversible ski mask (orange/camouflage), an orange sweatshirt, a knife and black shoes. Video footage from RJR showed a man in an orange sweatshirt, orange ski mask and black shoes entering and exiting the facilities soon after the arrival of Lois and Bill Cobb. The same individual left the building 2 minutes after Adam Fuehrer and Robert Fakler arrived. WDAY TV

11/12: RJR WDAY TV

12/12: Among other things, investigators found a business card for RJR in Chad Isaak's wallet Contributed / Morton County Clerk of Courts

On April 1, 2019, police responded to a suspicious incident at RJR Maintenance and Management in Mandan, North Dakota. There, they found four people viciously murdered, and the murderer at large. The crimes stunned and astounded the community and sent shock waves of terror across the prairie.

Authorities soon arrested a local chiropractor named Chad Isaak, who was later sentenced to life in prison for the cold-blooded killings. Isaak refused to admit guilt or provide any motive. He took his own life at the North Dakota State Penitentiary on July 31, 2022.

In Season 9 of the Dakota Spotlight true crime investigative podcast, host James Wolner will re-examine this recent case. His exploration is a personal one: He was working in Mandan at the time of the murders and joined the first police press conference, his first step into true-crime podcasting journalism.

Follow along as Wolner re-examines the morning of the murders, the hunt for the killer, his arrest and trial. He’ll seek to better understand the case and the killer’s motive, and remember the lives of those slain.

• Joe Arenz: Special agent with the North Dakota Bureau of Investigations. Arens was the lead investigator and worked on the case for two years.
• Gabriel Goter: Morton County assistant state's attorney and lead prosecutor in the trial of Chad Isaak.
• Justin Krohmer: Detective at the time at the McLean County Sheriff's Office. Recognized the suspect's white pickup truck in the photograph distributed to law enforcement. When he attempted to covertly photograph Chad Isaak's vehicle on the morning of April 4, 2019, he found Chad Isaak staring at him out the window.
• Susan Krohmer: Justin Krohmer's mother. Susan had an appointment at Chad Isaak's chiropractic clinic on the day he was arrested. Law enforcement used the knowledge of this appointment to anticipate when Isaak would leave his residence and plan for the detainment.
• Wade Krohmer: Justin Krohmer's father and captain at the time at the McLean County Sheriff's Office. Worked with Justin to compare the photographs of Chad Isaak's vehicle with the photograph distributed to law enforcement.
• Aaron Matties: Detective at the McLean County Sheriff's Office. Aaron assisted Justin Krohmer in getting photographs of Isaak's vehicle, which ultimately led to his detainment and arrest.
• Curt Olson: Patrol sergeant at the McLean County Sheriff's Office. One of many officers to assist with the detainment of Chad Isaak.

• Tanner Arthaud: Along with Kylan Williams, a Metro Area Ambulance paramedic who received a call for a possible cardiac arrest at RJR. They soon discovered multiple puncture wounds on Robert Fakler's chest and asked police on scene to see if the scene was safe.
• Jamie Binstock: Robert Fakler's daughter. A resident of South Heart, North Dakota at the time, she received a call from her mother Jackie Fakler who said she thought Robert had had a heart attack at RJR. Jamie and her husband packed up their kids and headed to Mandan where later that evening they all learned that Robert had been murdered. Also killed were Lois Cobb, William Cobb and Adam Fuehrer.
• Amy Cobb: William Cobb's adult daughter of Springfield, Illinois. Amy was at work when she received a call from her step-sister, Briann Miller – Lois Cobb's daughter – wondering if she'd heard from their parents. Social media and friends were contacting Briann about something going on at RJR where their parents both worked.
• Lois Cobb: An employee at RJR and wife of William Cobb, she was killed on April 1, 2019.
• William Cobb: An employee at RJR and husband of Lois Cobb, he was killed on April 1, 2019.
• Jackie Fakler: Robert Fakler's wife and co-owner of RJR. Jackie arrived at RJR to discover ambulance personnel tending to Robert and police officers ushering people out of the building. She called her daughter Jamie and told her she thought Robert was having a heart attack.
• Robert Fakler: Co-owner of RJR with wife Jackie Fakler, he was killed on April 1, 2019.
• Adam Fuehrer: A technician at RJR, killed on April 1, 2019.
• Melissa Fuehrer: Widow of RJR Maintenance & Management victim Adam Fuehrer. Adam and Melissa had two sons together.
• Gabriel Goter: Morton County assistant state's attorney and lead prosecutor in the trial of Chad Isaak.
• Pat Haug: Lieutenant at Mandan Police department who investigated the RJR homicides alongside the North Dakota Bureau of investigations.
• John Henry: Second Mandan patrol officer to arrive at RJR. He noted blood droplets that seemed out of place and then searched the building. He discovered the bodies of Lois Cobb and Bill Cobb in an office area and Adam Fuehrer behind a workbench in the shop.
• Chad Isaak: A 44-year old chiropractor from Washburn, North Dakota, who was found guilty of all four murders at RJR. He hanged himself in prison on July 31, 2022.
• Briann Miller: Lois Cobb's adult daughter of Springfield, Illinois. Briann received a phone call from a friend in North Dakota who said social media and news outlets were reporting something happening at RJR where Brian's mother and step-father worked. She immediately called her step-sister Amy Cobb (Bill Cobb's daughter).
• Garrett Stepp: Third police officer to arrive on scene. He helped officers Henry and Tessness search and secure the building. Later he secured Bill Cobb's missing vehicle when it was discovered parked at a nearby business. There appeared to be blood smears on the door handle.
• Bruce Tessness: Mandan Police patrol officer. First police officer to arrive on scene. He immediately began assisting paramedics tending to Robert Fakler. Later he searched the building alongside officers John Henry and Garrett Stepp. Three more bodies were discovered.
• Andrew Tryhus: Morton County sheriff's deputy. Responded to the scene at RJR where he assisted the Mandan Police Department with several duties.
• Chief of Police Jason Ziegler: Chief of the Mandan Police Department, who fielded questions in the wake of the April 1, 2019 murders at RJR Maintenance and Management.
• Kylan Williams: Along with Tanner Arthaud, a Metro Area Ambulance paramedic who received a call for a possible cardiac arrest at RJR. They soon discovered multiple puncture wounds on Robert Fakler's chest and asked police on scene to see if the scene was safe.