Dwalin, to answer your question about why did he only receive eight years in prison, I think I might be able to clear it up for you.

Here in Canada we have three (3) types of Murder charges:

1st Degree Murder (Life Imprisonment with chance of parole in 25 years)

2nd Degree Murder (Life Imprisonment with the chance of parole in 10-25 years)

Manslaughter - Unintentional kill (If life imprisonment is ordered, there is no minimum time that is automatically required to be served before parole eligibility. Those sentenced to life imprisonment for manslaughter would be eligible for parole after serving 7 years. It may be possible for the court to delay parole eligibility for a life sentence for manslaughter up to 10 years. It is also common for manslaughter convictions to result in sentences other than life imprisonment. A 9 year sentence, which is not uncommon, would allow the offender to be paroled after serving 3 years of his sentence. If a firearm is involved in the offence, a minimum sentence of 4 years is required [parole eligible after serving 1/3rd of this]).

Since Cotroni was convicted of Manslaughter he had to serve a minimum of 4 years since a firearm was involved and it was up to the judge to allocate a sentence, thus he was given eight years at the discretion of the judge.