BOISE -- A Boise man on trial for the murder of a 20-year-old is trying to convince a jury that he shot the victim in self-defense after the younger man attempted to stab him with a knife.

Adam Bodenbach, 30, could spend the rest of his life behind bars if convicted of killing Ryan Banks, his friend and one-time neighbor in the Park Village Apartments near Boise State.

Prosecutors are asking jurors to reject Bodenbach's claim that he killed Banks to protect his own life. Prosecutor Whitney Faulkner painted a picture of a defendant so bent on revenge that he carried a gun across the complex to lay in wait for his victim in sub-zero temperatures.

“There was no reason for Ryan Banks to be killed, and there was no justification for his death,” Faulkner said.

Banks and Bodenbach met when they lived next door to each other at the apartment complex. Although Bodenbach and his roommate, Jacob Kimsey, later moved to another unit on the other side of the the complex, all three men remained friends, often gathering in Banks' apartment to play video games.

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The events that led up to the shooting began to unfold the night of Jan. 5. Faulkner said Banks and Kimsey were hanging out together when they decided to head over to Bodenbach's apartment.

“When they got there, the defendant was pretty amped up," she recounted. "He wanted to take Jacob’s car, and he wanted to go buy drugs.”

Kimsey wasn't sold on the idea. Boise was socked in with snow and freezing temperatures, and the streets had become perilously icy.

The roommates argued, Faulkner said. As the dispute appeared to be about to turn physical, Banks intervened.

Defense attorney Doug Nelson said Banks escalated the fight.

“He gets in the middle and grabs Adam, moves him from the common living area into Adam's bedroom to the point where Jacob has to grab Ryan – who is on top of Adam – and do everything he can to pull Ryan off," he said.

Banks was furious after the fight, and Kimsey took him back to his own apartment, the defense attorney said.

Faulkner said Kimsey returned to his own apartment to find the suspect "frantically searching for his gun."

“He was muttering to himself, saying things like ‘Ryan loved that thing. I know he has it. He took it, where is it, I can’t find it. I know he has it,’” she said.

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Both the prosecution and defense say Kimsey tried to calm Bodenbach down, assuring him that Banks had not taken his 9mm. Kimsey left the apartment, heading back to Banks' place to watch TV.

After some time, the victim and Kimsey headed outside to smoke a cigarette, Faulkner said, and spotted Bodenbach standing outside with a gun.

The gun was pointed at Banks, she said.

"[Bodenbach] said something about, ‘you thought I was bluffing?’ and ‘you disrespected me,’” Faulkner said. “Ryan went to try to grab that gun. As he did that, one shot was fired. Ryan hit the ground, and he never got back up.”

In a panic, Kimsey tried to drag his badly injured friend away. He thought he was pulling Banks into the victim's own apartment, but dragged him instead to the apartment next door, according to the prosecution.

Inside was a young woman who had just moved to Boise that same day, Faulkner said. From her bedroom, the woman heard the gunshot, then shuffling noises in her living room.

The prosecutor said the woman peered out of her room to see Kimsey dragging the victim inside, then quietly shut the bedroom door and called 911.

Bodenbach and Kimsey also each dialed 911, with Bodenbach telling dispatchers in the recorded call that a man had attacked him inside his apartment, and that he had shot the attacker in the leg. The handgun would be on the counter in his apartment, he told authorities.

In reality, the bullet had hit Banks in the chest, entering underneath his armpit. Kimsey, the first officers to arrive, and paramedics all tried to save his life with CPR and other measures, but at 12:38 a.m. on Jan. 6, Banks died on the apartment floor.

Police found Bodenbach in the complex - a cell phone in one hand and a large knife in the other, Faulkner said - and took him into custody. Prosecutors say the officers found the gun, along with drugs and drug paraphernalia, inside Bodenbach's apartment.

Faulkner said Bodenbach had already made up his mind to shoot Banks during or immediately after the fight in his apartment.

“There is no raincheck for self-defense," she said. "He decided he had that right, and he went in pursuit of it.”

But Nelson argued his client was afraid, not vengeful, when he pulled the trigger.

The attorney said that after the fight, Bodenbach had been motivated by concern for his roommate - Kimsey - when he grabbed his gun and walked across the complex to Banks' unit.

“He’s worried that, if Ryan’s in this kind of an agitated state – is Jacob safe?” Nelson asked.

Nelson said the defendant knocked on Banks' door, and was instantly attacked.

“Immediately, Ryan lunges for Adam, grabs his wrist, pins him to the wall with his forearm,” the lawyer said, noting that Bodenbach weighs a slight 140 pounds to Banks' nearly 250.

"That’s when, Adam says, the knife comes out in reverse grip, and it’s coming at him – at Adam,” Nelson said. “He can’t aim very well because he’s got the gun pinned to the wall, but he pulls the trigger.”

Banks dropped.

Nelson said another resident of the complex heard the commotion, and came out after the injured man had already been pulled inside. Bodenbach, who was on the phone, allegedly told the man "he came at me with a knife" and pointed to a large knife near where the shooting happened.

The resident reported he saw Bodenbach pick the knife up off the ground, then head back to his own apartment.

Once inside, Bodenbach placed the gun on the counter and took several Xanax "to calm his nerves," Nelson said.

Police took him into custody, then brought him to the hospital after he complained of pain from the earlier fight. Although the defense attorney acknowledged Bodenbach was "kind of all of the place" while speaking to detectives and doctors at the hospital, his account of Banks wielding a knife remained constant, Nelson said.

“One thing he’s consistent with is, he shot Ryan Banks in self defense," Nelson said. "Ryan was going to stab him with the knife, he didn’t want to do it, but it was either going to be him or me.”

Banks was known to carry that knife - a distinctive "fighting knife," the defense attorney said. Testing later revealed the victim's DNA was on the knife.

The attack would also not be out of character for Banks, Nelson said, describing the victim as a "lost soul" who Bodenbach had taken under his wing and tried to mentor.

Bodenbach's lawyer said the defendant considered Banks "a good kid with a violent side." Banks described himself as a "fighter," and Bodenbach had previously had to talk the victim out of going to another fight with the same knife, Nelson said.

In addition to the first-degree murder charge, Bodenbach also faces a charge of possession of cocaine and a possible sentencing enhancement for use of a deadly weapon. He has been held in the Ada County Jail on a $1 million bond since his January arrest.

The trial is scheduled to continue Thursday, and could last until the end of the month.