An man who says he watched as Colin Koehler murdered 19-year-old Holly Boutilier took the stand this morning in Koehler’s murder trial. 28-year-old Justin Ptaszynski told the jury how he watched in shock as Koehler stabbed Boutilier. Ptaszynski says Boutilier fell to her knees and started to cry before Koehler slashed her throat.Ptaszynski says he then took off running but ran into a dead end. He says Koehler came up behind him, and feeling as though his life was in danger, he left the waterfront with Koehler. Ptaszynski says he stayed the night in Koehler’s Bangor apartment feeling like a prisoner. Ptaszynski says Koehler would only let him use the bathroom with the door open and he had to leave his cell phone with Koehler. He also said Koehler slept in front of the door so Ptaszynski couldn’t leave. He said Koehler washed the knife he used to kill Boutilier and hid it in his apartment before eventually hiding it across the street from his apartment where it was found by police in a retaining wall at a church. Ptaszynski also admitted he lied to the police in initial interviews about the murder, saying he wanted to “lessen his involvement” in the crime. He also admitted to getting rid of his own shoes that he wore the day of the murder. The defense is set to cross examine Ptaszynski this afternoon. Defense attorney Richard Hartley says Ptaszynski is not a credible witness and is just “out to save his own skin.”Ptaszynski was convicted of hindering apprehension and is currently serving a 10 year sentence at the Maine State Prison in Warren.A man who took the stand earlier today, Dustin Bayrd of Bangor, claims Koehler confessed to murdering Holly Boutilier.Bayrd was best friends with Justin Ptaszynski, the man police say was an eyewitness to the killing. Bayrd testified in court this morning that after the killing, Koehler and Ptaszynski met Bayrd at work and walked back to Koehler’s apartment.Bayrd says Koehler said, “I took her out.” Bayrd says Koehler then threatened to kill him if he told anyone.