Closing arguments began Thursday in the trial of an NYPD officer who shot a man in Brooklyn last year, killing him.

"The facts were clear through the whole trial, even when Isaacs took the stand yesterday," said Victor Dempsey, Small's brother. "The fact was Wayne Isaacs murdered an unarmed man and left him in cold blood."

Relatives of a man shot dead by off-duty police officer Wayne Isaacs said all they can do now is wait as a jury begins deliberating whether Isaacs was justified in killing Delrawn Small after a traffic dispute on Atlantic Ave. in Brooklyn on July 4, 2016.

The jury ended its first day of deliberations without a decision.

Isaacs, an officer in the 79th Precinct, is charged with second-degree murder and manslaughter.

"Glad the jury has got this case. We can start to end the false narrative that's associated with this case. We can have the jury speak on it," said Stephen Worth, Isaacs's defense attorney. "So we look forward to the jury's earnest deliberations."

In his closing argument, Worth said Isaacs acted in self-defense after Small got out of his car at a red light and approached Isaacs's car window — an encounter captured on a grainy surveillance video.

"That day in July was not Mr. Small's best day," Worth said. "On that day, he was drunk, he was dangerous, and he was assaultive."

Assistant Attorney General Joshua Gradinger challenged the defendant's testimony that he was punched by Small. He said Isaacs had no legal justification to shoot the victim.

"That was not a smart decision for Delrawn Small to get out of his car. But," the prosecutor said. "he didn't deserve to die for that, and it certainly didn't give this man the right to execute him."

"Looking forward to the jury coming back with a guilty verdict," said Wenona Small, Small's widow. "The attorney general is doing a great job and looking for a conviction with a long-term prison sentence."

Jury deliberations got off to a rough start after the jury passed a note to the judge declaring that Juror Number Five was being uncooperative and should be replaced by an alternate. The judge rejected the request after he and the lawyers in the case questioned the juror in a back room.

Isaacs took the stand in his own defense Wednesday.

He told the jury he feared for his life when he pulled his handgun and shot and killed 37-year-old Delrawn Small.

Prosecution witnesses testified earlier that the off-duty officer cut off Small's car.

But Isaacs told jurors that did not, saying he was driving with the flow of traffic.

Isaacs testified he fired three shots, but only after Small struck him in the face through the driver's window.

"It's Mr. Small who chose to turn this into a violent confrontation that's what has to be remembered here," said Worth.

"I thought I was going to lose my life at that point," Isaacs said. "That's the only reason: I had to stop the threat from losing my life."

But surveillance video shows that Small was immediately shot as he approached the car.

The video was not played during Isaacs's testimony.

During cross-examination, the prosecutor made the jury aware of what Isaacs could have done instead of shooting, such as rolling up his window or shouting "Police. Don't move."

Asked why he simply didn't drive off, Isaacs said, "That would not have been a good decision."

Isaacs also was grilled about failing to mention Small when he called 911.

Prosecutor: You never told her there was a dying man on the scene?

Isaacs: No.

"Today was probably the worst day of this trial, listening to this man and watch him on that stand and lie and cover up what he did," Dempsey said Wednesday.

Isaacs faces 25 years to life in prison, if convicted of second-degree murder.