There are different types of murder: Attempted murder and unintentional murder (manslaughter). The latter is normally divided into two categories e.g. purely unintentional murder or criminally negligent murder.
The example of purely unintentional murder would be if you shot at an animal and shot a person in the woods beyond the animal in which case the blood money is taken from the sane individual (father and son and male relatives of the murderer).
Criminally negligent murder or homicide is where the defendant kills only with an intent to cause serious bodily harm in which case the guardian can take blood money from the murderer himself.
Vehicular homicide (also known as vehicular manslaughter) involves death that results from the negligent operation of a vehicle, or more so a result from driving while committing an unlawful act. Such a murder is included in the category of purely unintentional murder or in the criminally negligent murder depending on the circumstances. In either case, it is obligatory on the person to pay blood money (diya) to the heirs. If the blood money is paid by an insurance company, the driver will no longer be liable. In fact, there are some countries with corrective punishments the observance of which depends on the same countries.
 - Araki, Muhammad Ali, Al-Masail Al-Wazehah, vol.2, pg. 181, Maktab al-E'lam al-Islami, Qom, 1414.