2 attacks on 2 Michigan women, one perpetrator: How investigators pieced together clues to catch a killer

Jessica Heeringa, a single mom working at an Exxon gas station in Norton Shores, Michigan, went missing in 2013.

Among the few clues investigators found at the scene were a small drop of blood and reports of a mysterious silver van.

In 2014, people driving along a Dalton Township, Michigan, road found the body of a woman with gunshot wounds to the back of her head.

Shell casings were found by the side of the road along with the victim’s belongings. The victim was later identified as Rebekah Bletsch.

For years investigators working on these separate crimes were unable to locate any suspects in either case.

But one teenager's frightening encounter with a gun-wielding stranger two years after Bletsch's murder would ultimately lead investigators to the man they said had killed both Bletsch and Heeringa.

A "20/20" episode airing Feb. 2 at 9 p.m. ET and streaming on Hulu the next day takes a look at the five-year investigation and prosecution into the cases and includes interviews with key investigators and the victim who helped lead police to an arrest.

On April 26, 2013, a customer at the gas station where Jessica Heeringa worked thought it suspicious that there was no clerk at the store and immediately called 911. Heeringa's car was still parked in the lot.

At first, investigators said nothing appeared to have been taken as Heeringa was getting ready to close for the night. And there were no signs of forced entry.

After further digging, detectives found a drop of blood, the cover of a handgun laser sight and what looked like tiny batteries.

Susan Follett, who worked at the gas station but was off duty that night, told investigators that she and her husband were riding their motorcycles and noticed a silver minivan pull up to the station's lot.

"The van ducks behind the gas station. Doesn't go out in front where the pumps are, goes behind the gas station which, at that time of the night, it's kind of weird," retired Lt. Michael Kasher, of the Norton Shores Police Department, told "20/20."

Follett and her husband kept an eye on the vehicle and were able to make out the driver was a man, as the van left the station a few minutes later.

Despite getting some tips for months, investigators had no leads or suspects.

A year after Heeringa's disappearance, investigators in another part of Michigan responded to the call of a woman found with three gunshot wounds to her head.

Bletsch was found on the side of a road near her home in Dalton Township on June 29, 2014. Three bullet casings were found near her body, according to investigators.

Sgt. Lisa Freres of the Muskegon County's Sheriff’s Office told "20/20" that her team did not have much evidence to go on and could not identify a suspect.

"I hate to call it a cold case because we were still actively working on it, and we didn't stop, but we had no solid leads," she said.

Investigators in both cases would get a break nearly two years later, when a 16-year-old called 911 claiming that a man in a silver van attempted to kidnap her in his vehicle at gunpoint.

Madison Nygard told "20/20" that she was walking home by herself on April 16, 2016, after a late-night party when a man in a van pulled up and offered her a ride home. She initially refused, but then got in the van when he said she could use his phone to call home. She said the situation quickly became scary.

"I asked to use his cellphone, and he was like, 'It's dead.' And he's just staring at me the entire time, and I'm like, 'Let me out, let me out, let me out,'" Nygard told "20/20." "And he's just staring at me, and then that's when he reached under and grabbed his gun."

Nygard unlocked the door, jumped out of the moving vehicle, and ran for safety. Authorities said they believe the suspect attempted to shoot at Nygard but the gun jammed. Two unspent bullet cartridges were found near the scene, investigators said.

Investigators were able to find surveillance footage of the van Nygard described and, following an exhaustive search, were able to identify a possible owner. Nygard picked Jeffrey Willis out from a police photo lineup.

It was at this point that investigators started to piece together the connections between the teenager's alleged attempted kidnapping and the two cold cases.

Willis, a furniture factory worker, was a regular customer at the gas station where Heeringa worked and he was questioned by investigators, at the time of Heeringa’s disappearance, after they learned he owned a silver van.

"He had actually stopped into the gas station that night and Jessica was working," Chris Hare, a former corporal with the Norton Shores Police Department, told "20/20." "He recalls seeing her there and he said that he didn't have a relationship with her, didn't talk to her a lot. Just had seen her working…in the gas station."

Police said his van appeared clean when they searched it and that he had an alibi.

Investigators did not have evidence at the time to arrest or charge him.

When investigators interrogated Willis about the Nygard case, he mentioned the police questioning him in 2013 about the Heeringa case. When asked about Nygard's case, investigators said he told inconsistent stories about what he was doing that day.

Willis denied abducting Nygard.

In a video from the interrogation, Willis is seen getting defensive with investigators when they said they were going to execute a search warrant of his home and vehicle.

When detectives searched the vehicle, they found a hidden compartment in the van. The compartment had a padlocked toolbox with bondage equipment, syringes, vials of insulin and a laminated diagram of the human body, investigators said.

"And so, ultimately, he had this map, if you will, of where if I wanted a low dose where would I inject somebody? If I wanted a high dose or something to move rapidly, where would I inject somebody in order to make that happen," DJ Hilson, the Muskegon County prosecutor, told "20/20."

Injecting a non-diabetic with insulin can be deadly, according to medical experts.

Police also found a lockbox under the driver’s seat with a gun that investigators linked to the Heeringa and Bletsch cases, and ammunition that was also used in the crimes.

A search of Willis' home uncovered a portable hard drive with even more incriminating evidence, investigators said.

"They discovered a file folder labeled 'vics,'" Hilson said. "Inside that folder, there were two sub folders, one containing the initials of Rebekah Bletsch, the other containing the initials of Jessica Heeringa."

Prosecutors tried Willis for Bletsch's murder first and submitted evidence that showed Willis’ DNA was found on the weapon and blood, that matched Bletsch’s, was found on his athletic gloves discovered in his van. Wills took the stand and denied killing Bletsch.

Willis was convicted in Bletsch's murder on Nov. 2, 2017, and sentenced the next month to life in prison without parole.

During his trial for Heeringa's abduction and murder in May 2018, Nygard testified about her alleged attempted kidnapping.

Even though Heeringa's body was never found, a jury convicted Willis for Heeringa's kidnapping and murder on May 16, 2018, and again sentenced him to life in prison without parole.

Heeringa's family did not speak with "20/20" about the verdict. They have not publicly supported Willis’ prosecution and have never believed that he is the person responsible for her disappearance. They contend that she is still alive.

Prosecutors declined to pursue a trial in Nygard's alleged attempted abduction and dropped the charges because Willis was already behind bars for life.

Willis pleaded not guilty to the attempted abduction of Nygard.

"That was kind of like a huge slap in my face," Nygard said, addressing the prosecutors’ decision to not go forward with a trial for her case.

Hilson, who applauded Nygard's courage in going to the police and taking the stand, contended that there was no need to move forward with another case.

"He had been convicted of two separate counts of first-degree murder, so he’s essentially going to die in prison, and so, ultimately, I made the decision," he said.

At his sentencing hearing for Bletsch, Willis refused to sit and listen to victim impact statements. On his way out of court, he blew a kiss to her family.

"He got his way and got to walk out and not listen to us," Jessica Josephson, Bletsch's sister, said.

However, the family was able to be heard.

The sheriff asked Hilson if they could play audio of the family's statements during the transport from court to prison and he agreed.

"They played it loud and they played it for him over and over again," Willis' attorney Fred Johnson told "20/20." "He didn't stand up there and take it, but he heard it."

Following the events at Willis’s sentencing in the Bletsch case Rebekah’s family fought to prevent it from ever happening again.

Since 2018 the Rebekah Bletsch Law has ensured that those convicted in the state of Michigan have to hear the victim impact statements at sentencing.