BRIDGEVIEW, Ill. (WLS) -- Before autopsy photos of the 14-year-old girl were shown, the judge warned Kelli O'Laughlin's family and friends that those who could not keep their emotions in check should leave the courtroom during this stage in the murder trial of John Wilson Jr. Kelli's dad excused himself from the room. Kelli's mom, other relatives and supporters stayed.



O'Laughlin, 14, was stabbed to death in her Indian Head Park home in October 2011. Wilson is charged in her murder.



For 14 minutes, Cook County Medical Examiner Stephen Cina clinically described a dozen photos displayed on a large television screen in the courtroom. O'Laughlin was stabbed and cut eight times in her chest, neck and back.



Some in the courtroom cried softly at the sight of such a young girl dead and fully exposed on an examination table. One juror could be seen covering her eyes.



Next, prosecutor Guy Lisuzzo brought out the murder weapon: a roughly 13-inch kitchen knife.



On cross-examination, defense attorney John Paul Carroll produced a 12-inch ruler to symbolize the knife. Carroll held it to his own back and neck while repeatedly asking the medical examiner if it would have been possible for a person to stab themselves with a similar sized knife. Medical Examiner Cina repeatedly responded that - while possible - the cause of Kelli's death was not a suicide.



Wilson's defense attorneys have argued that O'Laughlin either killed herself or was killed by someone else.



Prosecutors also sought to address the lack of blood found on defendant Wilson's clothing. Cina told jurors that depending on the sequence of the eight stab wounds, it was likely there may not have been much blood released.



"Not like a psycho killer in a horror film," Cina said. Earlier this week, other experts testified Wilson's DNA was found on a knit cap left behind in the O'Laughlins' Indian Head Park home.



Also on Thursday, prosecutors revealed that a post was made on O'Laughlin's Facebook page the day after she died, presumably by the killer. It read, "Next time the b---- will do as told."



Testifying last for the prosecution was an FBI agent who tracked Wilson's cell phone and O'Laughlin's stolen phone on the days after the murder. He testified that on several occasions the two phones were in roughly the same area beginning in Indian Head Park the afternoon of the murder and then traveling to the far south and then north sides of Chicago the following day.



The prosecution expects to rest Friday morning, and the defense will then call its first witness. The case could go to the jury Friday.