It was six days before Christmas in 1979. Eighteen-year-old high school student Michelle Martinko had driven to the mall in her hometown of Cedar Rapids, Iowa, to buy a coat.
After leaving the mall, she walked to the family car, which she’d left in a dark corner of the parking lot. She turned on the engine to warm it up, and sat there for a minute. Then someone opened the door, pushed her over, and stabbed her 29 times.
One of the stab wounds to her chest penetrated her aorta, and she bled to death in the car.
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Six days before Christmas in 2018, her killer was finally arrested.
Michelle loved to dress up and style her blonde hair like Farrah Fawcett. Her family remember her as being "kind, sweet, funny, pretty and smart". She sang in the school choir and wanted to study interior design at university.
Michelle’s older sister, Janelle Stonebraker, says her mum Janet had five miscarriages before Michelle came along. Michelle was born when Janet was 44, and she was the "miracle baby".
Diagnosed with scoliosis when she was 12, Michelle had to wear a brace for two years to straighten her spine. Once the brace came off, she started getting a lot of attention from boys. One of those boys was Andy Seidel.
Michelle and Andy dated for two years before they broke up. It was Michelle who wanted to end the relationship. She later dated another boy called Mike Myrick, but Andy wasn’t prepared for her to move on.
"After they broke up, he wanted to know her every move, who she was dating, why she was dating that particular person," Janelle’s husband John told CBS.
On the night that Michelle died, she had gone to a choir end-of-year celebration, and then on to the mall. At the mall, she bumped into a few of her friends from school, as well as Andy.