How far is too far when it comes to self-defense in your home? A murder trial in Minnesota is sparking debate on this subject after a man fatally shot two teens who had broken into his home in 2012.

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Here's more background on the trial of 65-year-old Byron Smith from AP:

LITTLE FALLS, Minn.- Prosecutors say a Minnesota man who killed two teenagers after they broke into his house had been lying in wait in his basement with a book, some snacks and two guns.

Opening statements are underway in Little Falls for 65-year-old Byron Smith. The former federal government employee is charged with first-degree premeditated murder of 17-year-old Nick Brady and 18-year-old Haile Kifer.

Smith has claimed self-defense. Authorities say he went too far when he shot them repeatedly.

Assistant Washington County Attorney Brent Wartner described the sequence of the shootings. He says Brady was descending the basement stairs when Smith shot him in the chest, then the back and finally in the head after the teen had fallen.

Wartner says Smith then waited for Kifer to come downstairs and shot her 6 times.

Not surprisingly, Smith's defense team has an entirely different take on the events.

Defense attorney Steve Meshbesher says Smith's home had been targeted by burglars who took valuables and guns. Meshbesher highlighted one break-in about a month before the shootings in which someone kicked in a door.

He says Smith was terrified and had begun wearing a holster and pistol around the house.

Smith called authorities the day after Thanksgiving, 2012, saying he had killed the teenagers the day before after they broke into his home. He told police that while reading "heard door rattle," heard walking on deck and then a window break.

Martha MacCallum discussed the controversial case this morning with defense attorney Anna Yum and former assistant U.S. attorney Alex Little. Yum said one factor that will hurt Smith's case is that police said he had an audio recorder taping the whole thing.

"I think it's going to bolster the prosecution's argument that this was more about premeditation and deliberation than about self-defense," said Yum, also highlighting the fact that Smith never called police until a day after the shootings.

Prosecutors say Smith crossed the line when he continued firing on the teens even after they no longer posed any threat. Yum said the jury will have to decide whether Smith's actions were reasonable.

Little said the defense will have to convince jurors that Smith was truly frightened as an older person living alone. He said there are a lot of different verdicts that could come out in this case, including Smith being convicted on lesser charges or being convicted for first-degree murder for the second death, but not the first.

Judge Andrew Napolitano weighed in on this case on Shepard Smith Reporting. He noted that under Minnesota law, the defendant doesn’t have to prove he was in fear.

Furthermore, Judge Napolitano said that a jury may understand why the shooter said "you're dead." 

“The law understands because human nature understands that in the stress of the moment, if you really believe that this person is an intruder who could kill you, you’re not even going to count the shots. You’re not going to think or speak in the niceties with which we think and speak in polite society," he said.

Hear the rest of Judge Napolitano's thoughts in the clip below:

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