NEW YORK (CBSNewYork) — A Brooklyn teenager was convicted of murder and arson Thursday for setting a fire that left a police officer dead in a Coney Island, Brooklyn building.

Following a trial before Brooklyn Supreme Court Judge Danny Chun, a jury convicted Marcell Dockery, 18, in the April 2014 fire in a Coney Island Homes public housing building at 2007 Surf Ave., according to the Brooklyn District Attorney’s office. The fire killed NYPD Officer Dennis Guerra, 38, and seriously injured his partner, Officer Rosa Rodriguez.

Around 12:30 p.m. April 6, 2014, Guerra and Rodriguez responded to a 911 call for a fire at the building. They were overcome by toxic smoke upon arriving on the 13th floor, according to trial testimony.

Firefighters found both officers unconscious, and Guerra later died.

Police Officer Dennis Guerra (credit: NYPD)

Police Officer Dennis Guerra (credit: NYPD)

During the trial, prosecutors played Dockery’s confession to police. He said 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 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.

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.”

Dockery later rescinded his entire story, saying he was coerced by police.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

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.

In responding to the fire Dockery set at the public housing building, officers Guerra and Rodriguez entered an elevator and were overcome by the thick, black, burning smoke the moment the elevator door opened.

Rodriguez described the effects of her injuries at trial.

“I can’t breathe. I can’t walk. I can’t climb stairs. I can’t play with my kids anymore,” she said.

In a voice barely above a whisper because her lungs are damaged from the soot and heat, Rodriguez described the horrible scene. She said she and Guerra tried to find the exit door, and unable to see, they had to feel along the walls.

“We couldn’t breathe well,” she said. “I remember holding on to Guerra’s shoulders, I didn’t want to lose him.”

Rodriguez said she will likely need a lung transplant as a result of her injuries from the fire.

Dockery will be sentenced on June 14. He faces up to 25 years to life in prison, prosecutors said.

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