Question

There is a famous fictional story about Ronald Opus.
In brief:
On March 23, 1994, a man named Ronald Opus jumped from the top of a ten-story building in an attempt to commit suicide. As he passed the ninth floor, his life was cut short by a shotgun blast fired through a window. Neither the shooter nor the deceased was aware of a safety net installed on the eighth floor to protect the window washers, a net that presumably would have prevented his death.
Further investigation led to the discovery that an elderly couple lived in the room on the 9th floor from which the shot was fired. The old man had threatened his wife with a shotgun after an argument broke out between them. He became so upset that he could not hold the gun steady. So when he pulled the trigger, he missed his wife, and the bullet passed through the window and struck the deceased.

Usually, when a person intends to kill one person and mistakenly kills another, he is considered guilty of the murder of the second person. However, during the investigation both the old man and his wife firmly claimed that neither of them knew the shotgun was loaded.
It had long been the old man’s habit to threaten his wife with an unloaded shotgun; he had no intention of murdering her. Therefore, the killing of the deceased initially appeared to be accidental. That is, the gun had been loaded by mistake.
But in an intensive investigation in which the neighbors were questioned, a witness was found who testified that the couple’s son had been seen loading the gun about six weeks before the fatal incident. The investigation revealed that the mother (the elderly woman) had stopped supporting her son financially, and the son, knowing his father’s tendency to threaten her with the shotgun, loaded the gun expecting that his father would shoot his mother. The case once again became a murder investigation, and the couple’s son was suspected of the murder of Ronald Opus.
And then comes the final twist:
Further investigation revealed that the son, Ronald Opus himself, had become increasingly depressed in recent weeks over the failure of his attempt to bring about his mother’s murder. This led him to jump from the ten-story building on March 23, only to be killed by the gunshot fired from the gun he himself had loaded, through the ninth-floor window.
The police closed the case as a suicide.
What does the Rabbi think?
1. In terms of Jewish law, is this defined as suicide? (Meaning: is it forbidden to sit shiva for him, not say Kaddish, and the other laws concerning one who knowingly takes his own life?)
2. Is the old man guilty of murder, even if only unintentionally?