Always a reserved man, he had turned into a recluse in the three months before his spree. The World War II vet was unemployed and lived with his mother. During the war, he was reportedly a brave soldier who kept meticulous notes of every German killed, down to details of the corpse. He was honorably discharged in 1945, and returned home with a collection of medals and firearms. His bedroom was decorated with military items and set up a target range in his basement. His mother supported them by working at a factory while Howard hung around the house and attended daily church services.
He had trouble getting along with his neighbors, and his interactions with them deteriorated in the three months before his spree. He was considered a "mama's boy" and the subject of teasing. He arrived home from a movie theater at 3am Sept 6 to discover that the gate he had just built in front of his house had been stolen. This appears to be the final trigger. After sleeping until 8am he got up, dressed in his best suit and ate breakfast with his mother.
At 9:20 he left the house looking for his first victims. In only twelve minutes he would shoot at a total of 26 people, killing 13 and wounding several others. When he heard the sirens of the approaching police, he returned to his apartment and engaged in a standoff with police. He was eventually convinced to surrender, and was taken in for interrogation. Only at the end of the interrogation did they discover he had been wounded as well.
Charges were filed for 13 counts of "willful and malicious slayings with malice aforethought" and three counts of "atrocious assault and battery." He was eventually pronounced insane, making him immune to criminal prosecution, but was sentenced to life in a unit for the criminally insane.
Unruh's rampage was the most visible of a number of murders and suicides by WWII vets, and may have spurred the federal government to put additional resources into mental health treatment for World War II veterans.