Tuesday was the second day of testimony in the murder trial of Colin Koehler, who’s accused of killing a woman along the Bangor waterfront last year. The prosecution presented some of the most damaging evidence they have.The defense attorneys for Colin Koehler said they thought today would be the toughest day of testimony against their client. The state presented their star witness, 28-year-old Justin Ptaszynski took the stand and told the jury he watched in shock as Koehler murdered 19-year-old Holly Boutilier.Ptaszynski says Koehler stabbed her in the abdomen. He says Boutilier fell to her knees and started to cry before Koehler slashed her throat. He said Koehler washed the knife he used to kill Boutilier and hid it in his apartment before eventually hiding it across the street, where it was found by police in a retaining wall at a church.During cross examination, defense attorney Richard Hartley tried making it seem as though Ptazynski could have committed the murder and is lying to save his own skin. “What we know is that Mr, Koehler has repeated consistently over and over again that he was not there,” says Hartley. “So the question then is who might have done this. And certainly we can’t help but look at Justin Ptaszynski. He had the opportunity and he certainly and the motive for needing to point the finger somewhere else. That’s all we’re trying to do is bring that out to the jury.”Prosecutor Andrew Benson asked Ptaszynski, “Did you in fact kill Holly Boutilier?” Ptaszynski answered, “No.”Benson then asked, “Did Colin Koehler kill Holly Boutilier?” Ptaszynski answered, “Yes.”Benson also asked him: “What would you have done differently on the night of the murder?” PPtaszynski said, “I would have at least called an ambulance or tried to revive her or maybe fought back a bit…there’s a lot I would have done differently.”Ptasinski has already pled guilty to hindering arrest in this case and is serving a 6 year sentence at the Maine State Prison in Warren.Two other witnesses took the stand Tuesday. One was Dustin Bayrd of bangor who testified koehler admitted to him he killed Boutilier.Koehler’s ex-girlfriend also testified that Koehler admitted the murder to her as well and sent her text messages alluding to the fact that he killed Boutilier.The state will continue to call witnesses tomorrow. The trial could last into next week.