MANSFIELD - A superior court judge has thrown out the most incriminating statements accused murderer Mark Hayden made to police about the killing of a local high school senior last year, ruling they were made after Hayden requested a lawyer.

Judge D. Lloyd Macdonald agreed to throw out the last 10 minutes of an almost two-hour videotaped interview, but noted that "it is fair to characterize the entire content of the interview as incriminating," according to the six-page ruling.

Hayden's lawyer, Francis O'Boy of Taunton, wanted the last portion of his client's statements thrown out as evidence because Hayden decided to invoke his right to a lawyer.

The prosecution had argued that his request during an exchange toward the end of the interview was ambiguous.

Hayden, a 19-year-old high school dropout, allegedly fatally shot 18-year-old Mansfield High School senior Andrew Colwell in the head in Colwell's SUV last July 7 in what police say was a drug deal gone awry. Hayden was arrested the following day at South Station in Boston, where he obtained a bus ticket to Kentucky. He was interviewed by Mansfield Detective Frank Archer and state police Detective Chad Laliberte.

Hayden initially waived his right to a lawyer and denied he was involved in the killing, but changed his story when Archer told him the story was contradicted by his girlfriend, according to the court document.

Hayden then admitted he was with Colwell and a passenger in the vehicle to buy marijuana. He said he was in the back seat when the passenger pulled a gun on him and that the gun fired, striking Colwell, when he pushed it away, the court document says.

When pressed by the officers that they had information that Hayden had recently acquired a gun, according to the court records, Hayden denied it.

Archer later told Hayden that police had contradicted his assertions that he had not used his cell phone that night and gave Hayden a scenario in which he had the gun, but did not mean for it to fire.

Hayden then said he was going to tell the officers the truth and told them to "look at my eyes." However, Hayden appeared to have had a change of heart and asked for a lawyer.

"It seems that I'm the culprit. Seems like a need a lawyer," Hayden told the investigators, according to the ruling.

After a pause, according to the ruling, Archer then appeared to gather up papers while Laliberte asked Hayden for the truth and talked about an earlier discussion about his window of opportunity.

Hayden then said "this is the real truth" and "went on to decisively incriminate himself," the judge wrote without indicating Hayden's statements.

Macdonald's ruling came after a pretrial hearing in which the judge reviewed the videotape and heard testimony. The court found that police acted in good faith in pressing the defendant about whether he wanted a lawyer. However, he found that Laliberte's request after Hayden asked for a lawyer constituted a continuation of the interrogation, according to the ruling.

Hayden has pleaded innocent to murder. No trial date has been set.