OMAHA, Neb. (AP) - Hours before he opened fire on two principals at his high school, a Nebraska teenager calmly accepted a suspension for driving on an athletic field. He went home to speak with his father and some friends - all the while giving no hint of turning violent, police said Thursday.
But after his father left to run errands, 17-year-old Robert Butler Jr. took a handgun from a closet and headed back to the school to confront the administrator who had punished him.
Butler, whose father is a detective for the Omaha Police Department, asked to see the assistant principal and fatally shot her in her office with his father's service weapon. He then wounded the principal and fled before killing himself.
Authorities on Thursday outlined the events that led up to the shooting, which unfolded at Millard South High School on the first day of class after holiday break.
Butler had transferred to Omaha in the fall from a school in Lincoln, about 50 miles away. On New Year's Day, he had been cited for criminal trespassing after driving his car on the school's football field and track, police said.
Butler was called out of class at 8:10 a.m. Wednesday to meet with Assistant Principal Vicki Kaspar. The two talked in her office, and he was escorted out of the school at 9:23 a.m., police said.
Butler remained calm after learning of the suspension.
"He wasn't acting like an out-of-control student at all," Police Chief Alex Hayes said.
Butler's parents decided to transfer him to Omaha because he was having disciplinary problems in Lincoln and had not been listening to his mother, Hayes said.
Butler's father didn't have any reason to expect his son would turn violent because the teen did not seem distraught about the suspension and had no history of mental illness.
"He was disappointed with the discipline, but he wasn't acting angry," Hayes said.
When Butler's father, who normally works an evening shift, left the home for about 40 minutes to run errands, Butler took his father's handgun out of a closet, posted an ominous message on Facebook predicting he would do "evil things" and broke into a locked garage where his father had stored his car since the trespassing incident.
"When we, as police officers, leave our houses, we do not expect our children to commit crimes like this," Hayes said.
Butler returned to the school at 12:45 p.m., but he still did not seem upset and even took the time to sign in at the administrative office, asking to see Kaspar again.
"He walked into the school just like a normal student. He was not displaying any firearm or weapons," Hayes said.
Police said he had been in her office about four minutes with the door closed before he shot her. Butler then walked across a hallway and shot Principal Curtis Case.
Butler also fired at a custodian and missed, and debris hit a school nurse, who was not seriously hurt.
An unarmed security officer was sitting at a desk outside the school's main offices and saw Butler walking away. Butler pointed a gun at the officer, who took cover and wasn't shot.
A school resource officer who heard the gunfire called police.
The security officer gave police Butler's name and described his car, and at 1:35 p.m., authorities received a report of a suspicious vehicle about a mile from the school. Officers raced to the car and found Butler inside, dead from a self-inflicted gunshot wound.
The gun was his father's service weapon, a .40-caliber semiautomatic pistol that can fire up to 15 rounds. Butler fired seven rounds.