Twisted new details on a murder mystery out of Michigan: A single mother working at a gas station vanishes without a trace. Now it appears her disappearance may have been just been a part of a much larger sick and twisted plan.

Once a person of interest, Jeffrey Willis is charged in the kidnapping and murder of Jessica Heeringa.

The deeper cops dig, the sicker things get. Do investigators have a serial killer on their hands? And if he's the guy cops think he is, did he act alone?

Jessica Heeringa was working alone at a gas station in Norton Shores, Michigan, a bedroom community on the shore of Lake Michigan. Police say April 26, 2013 appeared to be a routine night until a guy in a silver minivan parks behind the building. A van is recorded on surveillance video from the cameras at the pumps. The gas station manager and her husband just happened to be driving by and told cops something just didn't seem right.

"What they saw was a male figure in the rear of the van with the back hatch open, the figure shut the hatch door and quickly opened it back up again," said former Norton Shores Police Chief Dan Shaw. "It appeared to them that he was moving something in the van like he was adjusting something."

Crime Watch Daily's Billy Jensen explains why tracking down that van was so difficult.

"She was looking at a car that was a silver Chrysler Town and Country minivan," said Jensen. "There are 15,000 of those minivans in Michigan alone. That's not even counting the surrounding states."

Sometime after 11 p.m. a customer walked in, didn't see anyone working, and called 911. When cops arrived, Jessica was gone. In the back room investigators found her jacket and her purse containing more than $400. The cash register was untouched. The trash can was by the door.

While there were security cameras outside, there were none inside, which might have recorded the abduction.

"This wasn't a robbery, but outside they do find one clue: One drop of blood," said Jensen. "They test it and it's Jessica's blood. That could have meant that she was ambushed perhaps when she opened the door to take out the garbage and she was struck potentially over the head and dragged into the van and taken away."

Police mounted a massive search using helicopters and K-9s, but the trail went cold.

Three years after Jessica Heeringa went missing, a dramatic and disturbing new development: An attempted kidnapping of a 16-year-old girl turns multiple investigations upside down.

In the same area, an attempted kidnapping and sexual assault of a 16-year-old girl, who was lost, walking on a rural road. She says a man offered her a ride. Once in the car he pulled a gun on her. The teenager managed to jump out of the moving van and run away. She later picked her alleged abductor out of a line-up: It's Jeffrey Willis.

Cops search Willis's house and his silver minivan, a van matching the description of the one seen at the gas station the night Heeringa went missing. Restraints and syringes were discovered.

Detectives say Willis's van is a vehicle almost "customized" for a predator.

"Investigators recovered multiple syringes of liquid that appears to be a drug or a sedative of some kind, and we recovered handcuffs and a rope," said Muskegon County Prosecutor D.J. Hilson. "This was a vehicle designed not only to kidnap but also take sexual advantage of women."

Police also find wire restraints and a ball gag, and on his home computer, images of child porn, women in bondage, along with "kidnap and kill" videos.

"There's other videos found where at the end of them, they murder in a 'acting' way, and we also found videos that show this that are not acted," said Norton Shore Police Det. Sgt. Chris Prevette. "They were real life."

In the case of the abducted 16-year-old, Jeffrey Willis was charged with kidnapping and assault with a dangerous weapon.

The developments in that case started investigators in the direction of two other cases: Jessica Heeringa, and the cold-blooded murder of Rebekah Bletsch, 36. A year after Heeringa disappeared, Bletsch was fatally shot in the head while she was jogging on a road. Her murder also unsolved.

During the search of Willis's van detectives say they found a .22-caliber handgun, and ballistics matched the bullets recovered from Bletsch's body and shell casings found at the scene. At his home, they also found files on a hard drive labeled "vics." And two subfolders with the initials: "RSB" and "JLH," For Rebekah Sue Bletsch and Jessica Lynn Heeringa. In those folders were photos of both victims, along with news reports about their cases. They even found a password to several websites - "j4l27h13" - Jessica's initials and the date of the day after her disappearance.

Willis was charged with Rebekah Bletsch's murder and possession of child pornography.

Crime Watch Daily has learned Willis used to work as a janitor at an elementary school. The principal says Willis spent a little too much time in the school computer lab.

"We had a suspicious URL pop up on our computer of a pornographic nature," said Amy Upham. The principal says Willis was fired immediately.

Crime Watch Daily obtained his termination letter that reads in part "... His inappropriate use of a school computer caused a student to be exposed to a web site that should have been for adults only."

Despite evidence found in his car and home, prosecutors didn't charge him with Jessica Heeringa's disappearance.

But then, another break: A second arrest. It was Willis's cousin, Kevin Bluhm, a prison guard with the Michigan Department of Corrections. He was first charged with lying to police about the Rebekah Bletsch case, and then again for lying about the Heeringa case. Bluhm's father says he was lying to protect his cousin.

Weeks later, Kevin Bluhm flips the script, telling investigators that Willis was responsible for the disappearance of Jessica Heeringa. Court documents revealed Bluhm told police days after Heeringa went missing that he had seen a blond woman tied up in the basement of a home previously owned by Willis's grandfather. He said the woman wasn't moving, and he believed her to be Jessica Heeringa. He also told police he was forced to help Willis take care of Heeringa.

He later recanted these stories. Kevin Bluhm eventually pleaded guilty to lying to police. He was sentenced to time served, until a new charge kept him from going free. Police said the evidence and interviews led police to charge Willis and Bluhm in the kidnapping and killing of Heeringa.

Reportedly, it was Bluhm's accounts plus credit card and phone records that led to Willis being charged with Heeringa's murder. Cousin Kevin Bluhm was charged with accessory after the fact.

A couple of months later at an evidentiary hearing, Willis took the stand and claimed guards violated attorney client privilege after they searched his cell and allegedly read the notes meant for his attorney. Four days after that, at a hearing to determine if there was enough evidence to have Willis stand trial for Heeringa's murder, more than 20 witness took the stand, including the 16-year-old who started it all.

Willis's defense attorney argued the other two cases aren't linked to the Heeringa case and that there was no direct evidence linking him to her disappearance.

After the four-day hearing, based on the evidence found in the minivan, the gun, the videos of victims being raped and killed, the folders found on Willis's hard drive and the connections to the 16-year-old's kidnapping and the murder of Rebekah Bletsch, the material was found to be relevant evidence as to the demise of Jessica Heeringa.

The judge handed down his decision: "Jeffrey Thomas Willis should be bound over to circuit court on the charges of open murder and on the charge of kidnapping."

But as her family now awaits some justice, there is still no trace of Jessica, and the search for her remains still continues.

Jeffrey Willis's defense team recently filed a motion to dismiss the Bletsch murder case. Currently, the judge has not made a decision on that motion.