The 52-year-old Jörg Kretschmer was found guilty of involuntary manslaughter, bodily harm caused by negligence, and the negligent abandonment of a weapon.
The prosecution told the Stuttgart court that Kretschmer had failed to prevent his son Tim gaining access to the licensed weapon and its ammunition. The 17-year-old took the gun from his parents' bedroom in March 2009 and killed 15 people at his former school, before committing suicide.
While some of the 43 joint plaintiffs called for a prison sentence of up to three years, state prosecutors demanded a two-year suspended sentence for the combined 28 counts of involuntary manslaughter and bodily harm caused by negligence, as well as violation of laws about storing guns.
The defence had called for their client to be acquitted on the grounds that he had already been punished enough by the situation. Kretschmer's lawyer said afterwards he would appeal the decision, on the grounds that the Stuttgart court had previously reached another verdict on negligence with weapons.
Speaking before the court's verdict, Hardy Schober, spokesman for the anti-gun lobby group Amoklauf Winnenden, said, "Even if it's just for a quarter of a year, he must go to jail." Schober lost his daughter in the massacre.
Afterwards, some of the relatives expressed disappointment with the severity of the sentence, though Schober said it was what he had expected. The mother of one of the teenagers killed said she could accept the verdict.
"The extent of the sentence is secondary," said Jens Rabe, a lawyer for the joint plaintiffs. He said it was more important that the court send out a clear signal by sentencing Tim's father for manslaughter, and not just for contravening gun laws.
Appearing in court last week, Kretschmer apologized and expressed his sympathy to the relatives of those killed. “I feel responsible for my son and for the mistakes I made,” he said.