NEW YORK (CBSNewYork) — A teenage boy’s confession was played in court Friday, in his trial for allegedly setting a fire that killed a police officer in Coney Island, Brooklyn.

As CBS2’s Scott Rapoport reported, the videotaped confession by Marcell Dockery, 18, provided a new look inside the emotional murder case. It also raised questions about Dockery’s past behavior.

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Dockery is on trial in the April 2014 fire in a Coney Island Homes public housing building at 2007 Surf Ave. The fire killed NYPD Officer Dennis Guerra, 38, and seriously injured his partner, Officer Rosa Rodriguez.

Police Officer Dennis Guerra (credit: NYPD)

Police Officer Dennis Guerra (credit: NYPD)

As has been reported previously, Dockery said in the confession that he set a mattress on fire because he was bored.

“I didn’t mean for the whole fire to come – just for a second,” Dockery said in the confession recorded by the Brooklyn District Attorney’s office. “Just because I was bored; I just wanted something to do instead of sitting in the hallway.”

Dockery went on to describe how he lit the fire.

“I lit the edge of the mattress,” he said. When an assistant district attorney asked for specifics, Dockery said he used a lighter.

“When I set it on fire a little bit, I could have sworn I blew it out,” he said.

Dockery went on to say in the 2014 videotaped statement that he started knocking on doors telling residents to get out because of the fire. Later, he went on to McDonald’s, and then he heard the police were looking for him.

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Dockery said he was terrified about what he had done.

“It was like, got so big so quick, I was scared to tell them, like, ‘Yo, I started this,’” Dockery said. “So you feel me? Like, I was just nervous in my heart.”

Prosecutors later started showing surveillance video of Dockery, sparking what they believe was the lighter he used to start the blaze.

As the Dockery interview played, the family of Officer Guerra, and Officer Rodriguez herself, watched without expression in the courtroom. They showed no emotion.

Dockery later rescinded his entire story, saying he was coerced by police. His attorney, Jesse Young, likewise alleged Friday that the confession was coerced.

He said Dockery went through a grueling 2 1/2-hour interview with police, referencing “the chamber of hell that he endured in that interrogation room.”

Dockery is charged with second-degree murder. The judge in the case said he expects it will go to the jury by next Tuesday.

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In his videotaped confession, Dockery admitted to setting fires going back to when he was 9 years old – including once trying to spell out his name in a bathtub in flames.