A youth who fatally stabbed a Victorian mother who gave chase after he and his friends egged her Lalor house has been jailed for five-and-a-half years for what a judge has described as a "senseless" killing.

But the sentencing judge has made recommendations that the boy, now aged 16, serve time in youth detention because of his age.

Rosa Mercuri, pictured at a New Year's party.

The boy, who cannot be identified, was 14 on July 3, 2011, when he killed mother-of-three Rosa Mercuri.

In sentencing him in the Supreme Court today, Justice Paul Coghlan said he was satisfied the boy had unintentionally killed her out of panic and in a bid to escape.