The heart stricken grandmother of a murdered newborn says she feels sick in the stomach that his killer could spend less than seven years behind bars.

Joseph McDonald, 23, was sentenced in Victoria’s Supreme Court on Tuesday to nine years’ jail after he pleaded guilty to child homicide.

The man will serve six years and eight months behind bars before he will be eligible for release on parole.

McDonald is a cannabis and video game addict, and shook seven-week-old Lucas in a fit of anger before returning to his video games at their Benalla home in Victoria’s northeast in October 2019.

The baby died five days later at a Melbourne hospital from severe head injuries.

When he was contented by Lucas’ mother at the hospital, McDonald ran off and hid in a horse shed in the southeastern suburbs for two days.

“He’s taken my grandson’s life away forever,” grandmother Sharon Mills said to 7NEWS.

Baby Lucas’ mother, Samantha Duckmanton, has been left devastated by the minimum jail term of six years and eight months along with Ms Mills.

“She just can’t stop crying. She just can’t believe how,” she said.

Family friend Maddy Newell described McDonald as “gutless” and “weak” and said she believes he would “think he really hasn’t done the damage that he’s done to us”.

Justice Stephen Kaye accepted McDonald showed some remorse for his violent actions.

He has already spent 410 days behind bars and this will count towards his sentence.

This article originally appeared on Over60.