Man on trial for son's massacre

A year and a half ago, a teenager in Germany took his father's handgun to school and killed 15 people before turning the gun on himself. So since he's dead, they're putting his father on trial for manslaughter:

Jörg K., a businessman, has been a gun fanatic and amateur marksman since his boyhood. He passed on his passion to his son, an adolescent he apparently didn't know well enough. As it turned out, Tim K. developed a hatred for the world and, using the weapon his father had hidden under his sweaters in a bedroom closet as protection against burglars, became a murderer. On March 11, 2009, the 17-year-old shot and killed 12 children and teachers at the Albertville secondary school in Winnenden, a small town located about 20 kilometers north of Stuttgart in southern Germany. He killed three more people and injured 13, some severely, while fleeing from the police. In the end the boy shot and killed himself.

From Der Spiegel. Now to be fair, he's also on trial for violation of Germany's gun control laws (the article doesn't make it entirely clear, but it sounds like careless storage of a firearm). Is that sufficient grounds to convict someone of manslaughter? Maybe, maybe not. But part of what bothers me is this:

The Kleischs could hardly imagine that K. didn't suffer in these moments. But the disturbing thing about it all is that he didn't seem to be suffering. Doris Kleisch says that she would have liked to shake him and "see if he felt anything at all."

A video that was shown in the courtroom shows how police in riot gear surrounded Jörg K.'s house on the day of the rampage. It looks like a scene from a war zone. Then K. appears in the video as he walks into the house with the officers, checks for the Beretta in a bedroom closet, just as he does every night before going to bed. "The weapon is gone," he says in a businesslike tone. Then he looks in the bedside table and says: "The ammunition is gone too."

"How did Mr. K. seem to you?" the chief judge asked the police officer who was at the scene. "Surprisingly calm," the policeman replied. "If it had been my house, I would have been more upset."

Now maybe he really doesn't care, but it seems more likely to me that he's suffering from post-traumatic stress disorder (after all, wouldn't you, if your kid did that?) And the families seem to be judging him as guilty based on what they see as failure to display sufficient emotion (if I recall correctly, that was believed by many to be a factor in the wrongful conviction of Lindy Chamberlain back in the 1980s).

But the biggest thing that bothers me about this is that the families, and the prosecution, seem to want to get their pound of flesh one way or another, and since the actual perpetrator is dead they have to pillory someone else. Is that their idea of justice?