Jeffrey Thomas Willis, a former factory worker already incarcerated at the Muskegon County Jail for other crimes including homicide, was charged in Septemeber 2016 by the Muskegon County Prosecutor's Office with the kidnapping and murder of Jessica Heeringa. Willis had been a frequent customer at her place of employment, he matched a police artist's sketch of a man seen "being real flirty" with her on the night of her disappearance, and his minivan matched the description of one witnessed at the crime scene and recorded on security cameras speeding away from her workplace at about the time she went missing. His co-workers told police that he was scheduled to work that night but that he never arrived, nor did he show up for work in the days afterwards. Police executed a search warrant for Willis's home and found pictures of her in a folder labeled "vics" on his computer. Police searched for her body near his home after a tip was called in on June 17, 2016, but found nothing. Police had previously searched for her body in and around a cabin in Mancelona owned by a friend of Willis's on May 20, 2016, but also came up empty. Soon after Heeringa's disappearance, a local resident saw Willis at the Mancelona property walking out of the woods with a shove

On December 13, 2016, a Muskegon County judge ruled that Willis will stand trial for murder and kidnapping charges in Heeringa's case. The judge decided there was enough evidence to call for a trial after four days of testimony during the preliminary hearing. Judge Raymond Kostrzewa noted evidence such as the folder on Willis's computer titled "vics" (possibly short for victims) which prosecutors say included a sub-folder titled with her initials, photos of Heeringa, and the date of her disappearance. They also found necrophilia and murder porn videos downloaded from the internet—some of which were simulated and some of which were real.

The trial for Heeringa's murder took place in May 2018. After 1½ hours of deliberations, the jury found Willis guilty of Heeringa's kidnapping and murder on May 16, 2018. He received a life sentence without parole a month later.

Four page handwritten letter. Letter is general content and is signed Jeff. Original matching handwritten envelope is included.