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The Unsolved Murder of Thera Dieleman

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Case File Overview

On September 15, 1988, 80-year-old Thera Dieleman got a ride into town to enjoy a day of shopping in Goderich, Ontario. Afterwards, she was dropped off at home and settled in for a relaxing evening.

Thera had been widowed two years prior, so in 1988 she lived alone in her home located at 806093 Oxford Road 29 (formally Lot 5 Concession 7), Blandford-Blenheim Township, RR 2, ​Innerkip, Ontario​. She did her best to keep up with the house on her own. But she was often checked on by family, friends, and neighbours who were eager to give her a hand any chance they could.

Thera Dieleman

Photo of murder victim Thera Dieleman
Source: CBC News

On the afternoon of September 16, Thera’s neighbour Ken Rusnell called to see how she was doing. Following repeated attempts, he became worried and headed over to her house at 2:40PM to make sure everything was okay.

After getting no answer at the door, Rusnell entered the home. Just inside the front door, Rusnell found Thera dead on the floor. An autopsy later determined Thera had been beaten and strangled to death. Evidence at the scene indicated she fought hard for her life, leading investigators to believe the killer sustained injuries during the attack.

Thera’s killer has yet to be brought to justice.

Case File Theories

Over the past three decades little has been released about potential persons of interest in this case. However, there are some key pieces of evidence that need to be discussed.

It is unclear from the coverage of the case if Thera was sexually assaulted. But the police did announce that nothing seemed to be missing from the home, calling into question if robbery was a motive. Regardless, I am unwilling to discount that the killer went to the home to rape and/or rob Thera. Perhaps the perpetrator was surprised by the fact she fought back, and this derailed them from their initial intent.

The police did tell reporters there was no evidence Thera knew her killer, although it is unclear how they came to this conclusion. Considering her body was found in close proximity to her front door, it is possible a stranger attacked her in the entrance of her home.

Some good news is that a vehicle has been linked to the crime. On the day of Thera’s murder, neighbours noticed a large truck parked in her driveway. Witnesses described it as “a red one-ton or five-ton flat-bed stake truck with dual wheels, black headboard protector behind the cab, and white lettering on the doors of the cab.” No one noted a plate number, but the truck was quite distinctive, which could help connect it to the murderer.

Similar truck

Example of suspect vehicle in Thera Dieleman case
Source: CTV News

In 2007 there was a break in the case. Due to advances in DNA technology, investigators were able to develop a DNA profile of Thera’s killer from evidence left on her body. Unfortunately, the male DNA did not match the samples taken from any person of interest. And there was even more disappointment when the police ran the sample through the national DNA databank and came up empty.

In August of 2018, the investigators released ​composite sketches of the suspect produced by using cutting-edge DNA technology. They generated an image of the suspect at the age of 25, as well as an age-progressed image of what he would look like when he was 55 years old.

Composite sketch of suspect

Suspect in Thera Dieleman  case
Source: CBC News

To generate these images, the Ontario Provincial Police (OPP) sent some of the DNA sample they acquired in 2007 to ​Parabon NanoLabs​, a company located in Virginia that specializes in DNA phenotyping – ​a process that predicts physical appearance and ancestry from DNA evidence. During ​DNA phenotyping, a ​DNA sample is “analyzed and scanned for traits, such as gender, ancestry, skin, eye and hair colour. These variables are then plugged into an algorithm which can produce a composite sketch.”

When asked what led them to use this new technology, ​OPP Detective Superintendent Ken Leppert explained, “​We have a DNA sample that we’re confident was from the culprit. We are confident that people from or who lived in the area when this crime occurred may have information on this case. ​This technology wasn’t obviously available in 1988. We see this as an opportunity to hopefully stimulate memories, recollections from back in 1988.”

Detective Superintendent Leppert, however, did make it clear that this innovative use of DNA is not going to generate a one-hundred-percent accurate replica of the perpetrator. Instead, it generates a “scientific approximation of appearance” that does not take into account ​“environmental factors such as smoking, drinking, diet and other non-environmental factors like facial hair, hairstyle, [and] scars.”

They may not be a sure thing, but these sketches are indeed the biggest lead in Thera’s case since 2007 when the DNA sample was first generated. All it might take to break this case wide open is for someone to look closely at the sketches and to make a previously overlooked connection.

Who do you think killed Thera?

Thera’s murder is still discussed in Innerkip today. Many residents in the small community knew her and her family well and have hoped for years this cold case can be solved. Thera was a strong, kind, and spunky woman. For example, the rural route she lived on was under construction that often inconvenienced her and her neighbours. Thera was not shy to share her views on the situation with the construction workers and offer suggestions on how they should go about the work differently.

Thera survived three years in an internment camp during WWII before moving to Canada in the 1950s, only to be eventually murdered in the “safety” of her quiet, country home. Her murderer has possibly enjoyed over thirty years of undeserved freedom, and it is past time for him to be brought to justice.

There is currently a $50,000 reward for information leading to the arrest and conviction of the person(s) responsible for the murder of Thera. Anyone with information about this case should contact the OPP at 1-844-677-9414 or Crime Stoppers at 1-800-222-8477.

“Thera Dieleman”​ – ​Ontario Provincial Police​ case file

“It sounds like science fiction, but police created this sketch out of a suspect’s DNA”​ – ​CBC News​ article

“Police hope new suspect composite, crafted using DNA, will reignite investigation into 1988 Ontario murder”​ – T​he Province article

“DNA used to create sketch of suspect in Ontario woman’s 1988 murder”​ Toronto Sun​ article

“DNA from murder scene create sketches of suspect”​ – ​National Post​ article

“Composite sketches of Thera Dieleman murder suspect released”​ – CTV News​ article

Interested in unsolved cases? Check out the disappearance of Clifford Sherwood and Georges Gumbley and the slaying of Dr. Danuta Kaczmarska.

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Published inUnsolved Murder Files



  1. Brenda Durant Brenda Durant

    The future potential for solving crimes using DNA and genetic genealogy is mind blowing. I get great satisfaction from the idea that there are criminals out there looking over their shoulder and wondering when their luck will run out.

    • Christine Christine

      Hi Brenda. Thanks for reading and for taking the time to post your thoughts on the website! I couldn’t agree more. It seems like every year that passes the advances in DNA technology become more and more mind-blowing. Like you suggested, I sure hope perpetrators are afraid. Even more, I hope it might deter others from committing crimes to begin with. Take care!

  2. Maria Maria

    I have two theories about the murderer
    1. It might be a total stranger who decided to rob the house but then surprised because Thera fought back and accidentally murdered Thera and leave her house asap because he didnt mean to murder her.
    2. It could be someone who had a revenge plan on Thera. I don’t know Thera’s full story but everyone can make mistakes and not everyone is forgiving easily. So he only murdered Thera and leave.

    I really hope I can dig further to this case since I feel really sorry that this happened to an old lady

    • Christine Christine

      Hi Maria. Thanks for reading and for sharing your thoughts. Yes, this is a baffling case with little information out there and lots of possibilities. Like you, I hope there are answers in this case one day soon. Take care.

  3. Deliahla Deliahla

    I can help solve it I solved one if you need help with anything or what ever case call me or text me at 720 320 0693

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