Xander Samaras When human remains were found in suitcases abandoned by the side of a rural Wisconsin road, a community was left shocked and searching for answers.

The first responding officer opened one of the suitcases and discovered a woman's decomposing body -- naked, bound with rope and in a fetal position.

"Nothing can prepare you for what you can see upon opening a suitcase and finding a corpse inside of it," former Town of Geneva Patrol Officer Eric Anderson recalled.

A new "20/20" episode follows the investigation that spanned from Oregon to Minnesota and even involved the FBI. ABC News' John Quiñones reports for "The Suitcase Murders," airing Friday, Oct. 16 at 9 p.m. ET on ABC and streaming the next day on Disney+ and Hulu.

You can get more behind the scenes of each week's episode by listening to "20/20: The After Show" weekly series right on your 20/20 podcast feed on Mondays, hosted by "20/20" co-anchor Deborah Roberts.

When Walworth County Sheriff's Office Detective Jeff Recknagel, now retired, arrived at the scene and opened the second suitcase, he found a black plastic bag with a woman's hand protruding out. Her fingernails were painted pink, and her body was bound with rope and appeared to be in a state of mummification.

Investigators found no identification at the scene, and extreme decomposition prevented them from obtaining DNA from the bodies.

"We had a tremendous amount of work in front of us to try to figure out -- first off, who the victims were, then to try to figure out how they had lost their lives, and then to try to figure out who was the person responsible for that," Recknagel told "20/20." Police expanded their search beyond Wisconsin. They learned about another case in neighboring Minnesota, where a woman disappeared under suspicious circumstances.

Months before the suitcases were discovered in June 2014, Farmington Police Department Detective Sergeant Lee Hollatz was investigating the disappearance of 37-year-old Laura Simonson.

In November 2013, Simonson, who struggled with mental health issues following the death of her 13-year-old daughter Alyssa earlier that year, abandoned her van in her mother's driveway. Inside were her cell phone, purse, medication, and a note instructing her mother what to do with the vehicle and all her belongings.

Kristin Scouton, Simonson's childhood friend, said she grew concerned because Simonson, who had six other children, would never abandon her family.

"Her kids were her life," Scouton told "20/20." "She would've never just voluntarily left her children." Detective Hollatz issued a statewide crime alert about Simonson's disappearance. In a stroke of luck, a front desk agent at a hotel about an hour's drive away, reported she recognized Simonson. She remembered that Simonson had stayed at the property several weeks prior with a man that she said made her feel uneasy.

"There's certain people you meet where the hairs on the back of your neck stand up. He was one of those," Kristi Bodunov told "20/20" correspondent John Quiñones.

Although surveillance video of Simonson and this man checking in was unavailable, a registration card with her signature confirmed that she had stayed at the hotel. Police were, however, able to obtain the checkout video that showed the man leaving alone.

As police worked to identify the unknown man, a friend informed detectives that Simonson was involved in an online BDSM dating community and had been communicating with someone with the username, "Mrhandcuffs." Doing some digging of his own, the friend eventually made a critical discovery that he shared with police. He uncovered Mrhandcuffs' real identity: Steven Zelich.

When Hollatz looked into Zelich's background, he learned something unexpected: Zelich was a former police officer in the Milwaukee area. Hollatz recalled running over to another detective to share the news.

"I go, 'You will not believe this,'" he said. "I'm going, 'Now what am I getting myself into?'" Zelich resigned in 2001 from the West Allis Police Department following multiple allegations that he had abused his authority to intimidate and harass women. He denied any wrongdoing.

Hollatz asked West Allis police to visit Zelich at his home. But when officers arrived, there were no signs of Simonson.

With promising leads hitting dead ends, the FBI and Wisconsin State Police joined the investigation. In March 2014, the two agencies interviewed Zelich -- he voluntarily provided a DNA sample, but denied ever meeting Simonson.

With no evidence of a crime or foul play, authorities could not move against Zelich, and the case stalled. Several months later, the discovery of the two suitcases in Wisconsin would crack the case wide open.

Aware of the Simonson case in Minnesota, Wisconsin investigators identified one of the victims as Simonson, in part through a distinctive tattoo on her ankle featuring a heart and her daughter Alyssa's name. DNA recovered from the rope wrapped around the second victim matched Zelich.

Zelich was brought in for questioning and ultimately arrested. He confessed to killing both women found in the suitcases, identifying the second victim as Jenny Gamez, a 19-year-old from Cottage Grove, Oregon.

He told investigators he met Gamez on the same online dating website where he later met Simonson. He claimed he accidentally strangled Gamez while engaging in "breath play," a sexual activity involving the restriction of breathing.

Zelich said he stored Gamez's body in his refrigerator for over a year before killing Simonson in Rochester, Minnesota, in a similar manner. Maintaining that Simonson's death was also accidental, he described placing her body in the trunk of his car and later moving Gamez there as well.

As the weather warmed, a co-worker mentioned smelling a strong odor coming from near Zelich's car. Zelich said he panicked and decided to dispose of the suitcases.

Ultimately, Zelich was charged with multiple counts of murder and hiding a corpse. He initially pleaded not guilty to all counts.

In 2016, Zelich pled guilty to first-degree reckless homicide in the death of Gamez and one count of hiding a corpse. He was sentenced to 35 years in prison and 10 years of extended supervision.

The following year, he pled guilty to second-degree murder in the death of Simonson and was sentenced to 25 years in prison. He also received an additional 10 years on two counts of hiding a corpse in Walworth County, Wisconsin.

While Zelich's convictions brought the case to a close, Simonson and Gamez's families continued to grapple with their loss.

"Anytime you lose somebody that's so close to you, like your sister, your life's never going to be the same," Gamez's foster sister Amanda Duron told "20/20." "There's always going to be that puzzle where there's always that one missing piece." Simonson's sister, Niki Carlson, said she keeps her sister's memory close.

"Not a day goes by that I don't think about her. I love her, and I miss her every day." Carlson told Quiñones. "I know they're all looking down on us trying to make sure we're safe."