culpable homicide

The same example is available in each and every textbook on IPC with such illustrations.  When A's intentions are clear to get Z murdered with a preconceived plan (like you see in our movies) this is not culpable homicide but cold-blooded murder if there is such a relationship between Z and A that can confirm a criminal nature.

When accused is not single person rather in plural number then the court is to decide the criminal liability of each member.

Joint liability, vicarious liability and Strict Liability are somehow akin to each other in a way that here liability is imputed. A person is not help liable for the actual act committed by him rather knowledge (S. 149) participation (S. 34) and presence at the place of occurrence makes him liable. The common thing among all is that a person is charged with the offence which cannot alone be constituted by his singular act.

If two or more persons engaged in the same criminal act may be guilty thereby or different offences. This is provided for under Section 38 of the Penal Code thus: “Where several persons are engaged or concerned in the-commission of a criminal act, they maybe guilty of different offences by means of that act.” For instance, A attacks Z under such circumstances of grave provocation that his killing or Z would be only culpable homicide not amounting to murder. B, having ill-will towards Z and intending to kill him, and not having been subject to the provocation, assists A in killing Z. Here, though A and B are both engaged in causing Z's death, yet B is guilty of murder and A is guilty only' of culpable homicide. The reason is that as the intention differs, so does their criminal responsibility. In the particular, illustration, there is no common intention, rather the intention is different, therefore, the liability is also different. Section 38, as a matter of fact, is the converse of Section 34.

where the accused shares in the commission of the offence though he does not commit it, the Penal Code makes a provision for his liability under Section 34 which runs thus: “When a criminal act is done by several persons, in furtherance of the common intention of all, each of such persons is liable for that act in the same manner as if it were done by him alone. In other words, where several persons unite with a common intention to effect any criminal object, all those who assist in the accomplishment of that object are really guilty, though some may he at a distance from the spot where the clime is committed and be ignorant of what has actually been done. 

Every man is responsible criminally for what wrong flows directly from his corrupt intentions, but no man, intending wrong, is responsible for an independent act of wrong committed by another. If one person sets in motion the physical power of another person, the former is criminally guilty for his results. If he contemplated the result, he is answerable, though it is produced in a manner he did not contemplate. If he did not contemplate the result in kind, yet if it was the ordinary effect of the cause, he is responsible. If he awoke into action an indiscriminate power, he is responsible. If he gives directions vaguely and incautiously and the person receiving them acted according to what might be presumed to have been his understanding of them, he is responsible.

Time pass academic question has to be solved by your tutor.