MARINETTE, Wis. -- Sam Hengel was no stranger to firearms. He was an avid deer hunter, and his family owned at least three 9mm pistols and a shooting range on their property at a remote Wisconsin cabin.
Hengel also drew a crude sketch depicting scenes of violence and warfare, but police say none of those facts help explain why the 15-year-old held his high school classmates hostage at gunpoint for six hours on Nov. 29 before fatally shooting himself when a SWAT team swarmed the classroom.
Marinette Police Chief Jeffrey Skorik told reporters Friday that detectives had closed their investigation without uncovering the teenager's motives. The months-long investigation included interviews with Hengel's family, friends, teachers, Marinette High School classmates and even his Boy Scout leaders.
"This is an inexplicable anomaly in the life of Sam Hengel as everyone knew him," Skorik said.
Skorik released 355 pages of investigative documents, including interviews that painted a portrait of a smart, quiet leader who was well-liked and didn't have problems with bullies. Hengel apparently acted alone and never gave those around him reason to suspect he was planning an attack, Skorik said.
"We still don't know why he did this and what his intentions were," Skorik said. "I don't know that we could have done anything differently that would have prevented this outcome."
Hengel didn't play violent video games, Skorik said, and there was no evidence to suggest he was emotionally distraught over a breakup or other issue. Toxicology reports came back clean.
Hengel's parents, who described their son as a speed reader and "a natural" with schoolwork, said they didn't think he had a girlfriend.
Skorik told The Associated Press that the boy had a good family life and a strong relationship with his father. He said Hengel had no known mental-health issues. Teachers and students saw nothing unusual about Hengel in the days and hours leading up to the standoff.
The police report included an undated drawing with Hengel's name on it. The sketch showed a helicopter dropping a bomb on a square labeled 'city' while a stick figure on the ground fires a grenade at the bomb. Bullets from the helicopter split another figure in half, and a paratrooper fires into trees. Elsewhere one stick figure pushes another off a steep hill.
Skorik told AP he didn't think there was any link between the drawing and the hostage incident.
"That picture shows a bomb, a helicopter, a parachute, an outdoor scene," Skorik said. "None of that has to do with the incident in the school."
The standoff unfolded in Marinette, a city of 12,000 people along the border with Michigan's Upper Peninsula some 50 miles north of Green Bay.
Samuel Oscar Hengel brought a backpack to class that contained his father's 9mm handgun and a .22 caliber pistol that apparently belonged to his grandfather, plus more than 200 rounds of ammunition and a pair of knives. He had more bullets in his pockets. His father told police that Sam had used the 9mm a week earlier to shoot clay targets on the family's shooting range at a remote cabin.
During the hostage-taking, Hengel fired three shots from one gun and laid another gun and the ammunition on a podium. He never pointed his weapon at anyone or made any demand except telling people not to leave.
His classmates tried to lighten Hengel's spirits by chatting with him, and he even laughed at times.
Some students, fearing they wouldn't survive, poured out their hearts in handwritten letters to loved ones. Some expressed love for their parents and apologized for being less than perfect children. Others asked loved ones never to forget them.
"Please, lord, save me and everyone else in this classroom. I won't ask for anything else," one student wrote. "I want life, I want to live. There's still so much to see and do. PLEASE GOD. It's not my time."
Eventually the principal came to the classroom after the father of one student called to say his daughter wasn't answering her phone. Hengel let the girl leave but ordered the principal out at gunpoint. The principal retreated and called 911.
Hengel eventually let five other hostages go, then fired three rounds at a telephone and a computer. SWAT officers, hearing the gunfire, broke down the door and rushed at Hengel. An officer grabbed Hengel's arm just as the teen pointed a gun at his own head and squeezed the trigger.
One hero of the standoff was the teacher, Valerie Burd, who earned praise for helping Hengel and the other students remain calm. A student had scrawled a note in the classroom hailing Burd for keeping the situation under control.
"She is the most amazing teacher ever. She is so brave & calm during this whole time," the note said. "She could have just ran at any time but she stayed & protected us with her life. She is my hero."