The trial for a teen accused of starting a fatal 2014 fire in a Coney Island apartment building resumed Thursday with six hours of witness testimony.

A doctor and three detectives took the stand in the Downtown Brooklyn courthouse, and dozens of other NYPD officers filled the room in a show of support for the victims.

As News 12 has previously reported, Marcell Dockery is accused of setting a mattress on fire in a Surf Avenue building. The fire killed NYPD Officer Dennis Guerra.

The doctor is the physician for the NYPD officer injured in the blaze, Rosa Rodriguez. Guerra was her partner.

The doctor testified that Rodriguez's lung capacity has been so damaged that it is comparable to one of a 100-year-old person. He told the court that she may need a lung transplant -- a procedure with only a 50 percent survival rate.

The prosecution maintains that the fire caused Rodriguez's injuries, but upon cross-examination, the doctor admitted that the injured officer has smoked half a pack of cigarettes a day for the last 15 years.

Two of the three detectives who testified helped interrogate Dockery after the fire.

One of them testified that the defendant admitted to having habitually lit small fires since he was 9 years old. 

The court adjourned midway through the third detective's testimony. The trial will resume Friday morning.