Thera Dieleman

Thera Dieleman, an 80-year-old widow, was a familiar and friendly face in the small community of Innerkip, Ontario. Having survived a Second World War internment camp, she was known for her resilience and spirit. After her husband passed away two years prior, she lived alone in her brown brick house on Oxford Road 29 in Blandford-Blenheim Township. She kept up with the house on her own but was frequently checked on by a network of caring family, friends, and neighbors. During the road construction near her home, she was known to bring refreshments out to the workers, offering them her two cents on how the job should proceed.

The day before her death, on September 15, 1988, Thera spent the day shopping with friends in Goderich. She was dropped off at home around 5 p.m. and had a phone call with someone shortly after. The following morning, Friday, September 16, her rural mail delivery arrived at 10 a.m. Later, this mail was found inside her house, opened. Concern grew when a relative tried to call her at 11:10 a.m. and again at 11:30 a.m., but the phone went unanswered. A neighbor, worried after repeated unsuccessful attempts to reach her by phone, went to check on her that afternoon. Finding the door unanswered, he entered the home and made a devastating discovery just inside the front door: Thera was on the floor, having been brutally beaten and strangled to death.

The Ontario Provincial Police (OPP) launched a homicide investigation. The post-mortem examination confirmed the cause of death and also revealed that Thera had fought fiercely against her attacker, who may have sustained injuries in the struggle. Investigators determined there was no evidence of robbery or sexual assault. A crucial piece of information came from witnesses who reported seeing a distinct vehicle in Thera’s driveway between 11:45 a.m. and noon that day. They described it as a red or brown flatbed farm truck with white lettering on the doors, dual rear wheels, and a black headboard protector behind the cab.

For years, the case remained cold, though not forgotten by the Innerkip community. A major breakthrough came decades later. In 2007, the OPP announced that new technology had allowed them to develop a DNA profile of a male suspect from biological evidence left at the crime scene. In the summer of 2017, investigators took another step, sending this DNA to Parabon NanoLabs, a Virginia-based company specializing in DNA phenotyping. This advanced technology generated composite sketches based on the genetic evidence.

On the 30th anniversary of the murder in August 2018, the OPP held a news conference to release the images. One sketch depicted what the suspect may have looked like at age 25, around the time of the murder, and the other was an age-progressed image of what he might look like at 55. Police explained that the sketches are scientific approximations, predicting ancestry, eye color, hair color, skin color, and face shape, but cannot account for environmental factors or things like hairstyle and facial hair. "We believe using existing DNA evidence in this innovative way will ignite memories to help us bring a resolution to Thera Dieleman's family and her community," Detective Superintendent Ken Leppert stated.

The murder of Thera Dieleman continues to haunt the region, and her case was highlighted in May 2026 among other unsolved homicides in southwestern Ontario. Despite the passage of time and the advent of new technology, no arrests have ever been made. "The individual that killed Mrs. Dieleman has had 30 years of freedom," Leppert said in 2018, "and if anything, that makes it of more concern to us as law enforcement that we want to bring that person before the courts and before justice."

A $50,000 reward remains in place for information that leads to the arrest of the person responsible for Thera Dieleman's death. The OPP continues to seek tips from the public, urging anyone with information, no matter how insignificant it may seem, to come forward. Anyone with information is asked to call the dedicated OPP tip line at 1-844-677-9414 or, to remain anonymous, contact Crime Stoppers at 1-800-222-8477.