Investigation Discovery’s ‘American Monster: Plus-One’ examines the 2016 murder of 24-year-old Melissa Thornton, a single mother of a then-two-year-old girl, who was killed in her bed at the Alexander Street home she shared with her sister Angela. The Saginaw, Michigan, native didn’t seem to have any enemies per se. But once investigations into her case began, it turned out that the man who had discovered her body and dialed 911, the father of her child, Robert Propp, was the one responsible for her untimely death. So, let’s find out all that there is to know about him, shall we?
Who Is Robert Propp?
Despite their nine-year age difference, Robert Propp and Melissa Thornton fell in love quite quickly back in the 2010s. So much so that when Melissa fell pregnant with their child, a daughter, they decided to become a family. However, by the time 2016 rolled around, their relationship started to crumble apart, especially as Melissa couldn’t handle his cocaine addiction. And so, in or around March, she broke up with him and moved in with her sister to start afresh. Yet the former couple remained in touch because of their history, even after Robert purposefully began to bump into her whenever she was out and about.
On July 5, 2016, the evening before the incident, Robert apparently followed his ex-girlfriend and her sister to a bar and then made his way to join their table. Though, as Robert’s obsessive behavior didn’t seem that dangerous to the sisters at the time, they even invited him back to their place. And that’s when everything changed. According to Robert’s own confession, made on July 7, he and Melissa had sex that night in her bedroom, following which they got into an argument that included Melissa hitting her ex in the eye with her elbow. This supposedly then led to the former couple stumbling off the bed and a dresser falling on top of them.
Changing his initial story from how he found her unbreathing on her bed on the morning of July 6, Robert detailed how the fall had knocked Melissa unconscious. He explained that he just picked her up, put her on her bed, covered her with the sheet, and walked out before returning more than seven hours later. It was then, he claimed, he realized that Melissa was dead. However, once the authorities questioned him about how then her cause of death was strangulation, Robert admitted to having wrapped his left hand around her throat and using his body weight to put pressure on her. And so, he was charged and arrested for murder.
Where Is Robert Propp Now?
Robert Propp stood trial for the open charge against him in 2018, wherein, after various testimonies, he took to the stands in his own defense and once again gave a modified version of the events that transpired. He admitted responsibility for his ex-girlfriend’s death but maintained that it was all unintentional. Robert claimed to have mistakenly killed Melissa while performing erotic asphyxiation (choking) during sex, which just went a bit too far. He withheld this version all this time, he testified, because he didn’t want their sex life to be scrutinized. But in the end, with all the evidence, he was found guilty of premeditated murder.
Because Robert had an open murder charge against him, the jury could decide whether they wanted to convict him of first- or second-degree murder. And after about two hours of deliberation, the jury’s verdict of first-degree murder was announced, which carries the mandatory sentencing of life in prison without parole. Therefore, today, Robert Propp, at the age of 37, is incarcerated at a Michigan State Prison, where he will remain for the rest of his natural life. As for his daughter, Willow, while no official information has been released about her custody, we think it’s safe to assume that she is now under the care of Melissa’s family.
Read More: How Did Melissa Thornton Die?