In the quiet city of Springfield, Missouri, the lives of 60-year-old Gary Tyrrell and his wife Jan were brutally cut short in the spring of 2014. Concerned when she couldn't reach her parents, their daughter Jessica went to their home on South Greenbrier Avenue on May 1st, where a grim discovery awaited. She found their cars in the garage, a sign that something was terribly wrong, and promptly called 911.
When police entered the home, they found a gruesome scene; Jan was deceased on the first floor, and Gary's body was discovered in an upstairs bedroom. The investigation that followed would unravel a story of betrayal and greed.
The initial investigation into the double homicide revealed that Gary Tyrrell had been beaten and shot twice, while his wife Jan died from blunt force trauma. There were no signs of forced entry, leading detectives to believe the couple knew their killer. While some valuable items were left untouched, a collection of rare coins belonging to Gary, a known collector, was missing, and there was an attempt to break into a safe. The estimated value of the stolen coins was $22,000. This led investigators to suspect someone known to the couple was responsible for the heinous act.
Suspicion soon fell on Mark Porter, a 53-year-old former school superintendent and a longtime friend and colleague of Gary Tyrrell. The two had worked together in the Mountain Grove school district. Investigators learned that Porter had significant gambling problems and had recently asked Gary for a loan of $250,000, which Gary had declined. A few days after the murders, Porter sold a substantial number of silver coins for over $18,000, which were believed to have been stolen from the Tyrrells' home.
The pivotal piece of evidence that solidified the case against Porter was DNA. A latex glove was found at the crime scene near Jan Tyrrell's body. Detectives were able to obtain a sample of Porter's DNA from a coffee cup he had discarded. The DNA from the glove was a perfect match to Porter's. Faced with this irrefutable evidence, Mark Porter was arrested and charged with two counts of first-degree murder. In a plea agreement to avoid the death penalty, Porter pleaded guilty to two counts of second-degree murder. He was subsequently sentenced to two consecutive life terms in prison. The judge at his sentencing made it clear that he believed Porter should never be released from prison for the brutal betrayal and murder of his friends.
