GRAND JUNCTION, Colo. (Court TV) — The mother of a 6-year-old boy who prosecutors say was strangled to death in 2016 testified during her ex-boyfriend’s murder trial, breaking down as she described the final moments with her son.
A photo of Martin Osinski is shown in court during the murder trial of Darin Thrailkill on Nov. 4, 2025. (Court TV)
Krystal Osinski took the witness stand in the Mesa County trial of Darin Levi Thrailkill, 38, who faces first-degree and second-degree murder charges in the death of Martin Osinski on July 2, 2016. Thrailkill was dating Martin’s mother and lived with the family at the time of the killing.
“I just remember holding him and telling him that I loved him and that mommy was sorry,” Osinski testified through tears, describing her final moments with Martin at St. Mary’s Hospital emergency room.
The emotional testimony revealed the tragic events of that summer evening when Martin was found unresponsive in his bedroom at the family’s trailer home in Grand Junction, Colorado. According to court documents, Martin died from asphyxia due to strangulation, with the autopsy showing petechial hemorrhages and moon-shaped marks on his neck consistent with manual strangulation. Thrailkill’s defense claims the boy died from a combination of aspiration pneumonia and asthma.
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Osinski described the chaotic scene when Thrailkill woke her up around 10:30 p.m., telling her something was wrong with Martin. She found her son unresponsive in his bedroom and immediately drove him to the hospital, where medical staff attempted resuscitation for more than 20 minutes before declaring him dead at 11:20 p.m.
“I knew something was wrong. I knew something was off,” Osinski testified about discovering Martin’s body.
FILE – This 2023 booking photo provided by Grand Junction Police Department shows Darin Thrailkill. (Grand Junction Police Department)
The prosecution’s case centers on evidence that Thrailkill was the only adult who left the living room with Martin that evening.
The case remained under investigation for more than seven years before authorities obtained an arrest warrant for Thrailkill in October 2023, according to Grand Junction Police. Thrailkill was located and arrested in North Port, Florida, on October 3, 2023. He was subsequently extradited back to Mesa County that November.
During her testimony, Osinski described Martin as a loving child who enjoyed video games and spending time with his siblings. She broke down multiple times while recounting their relationship and the events leading to his death.
If convicted of first-degree murder, Thrailkill faces a potential life sentence.
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