Murray was yesterday sentenced to the maximum four years in jail after being found guilty of the star's involuntary manslaughter.
However, Jermaine has now declared that Murray's prison time is "woefully insufficient" based on the former physician's "breathtaking disregard of the human life".
"True justice shouldn't feel as empty and pointless as this," The Sun quotes him as saying. "Justice is not having some clown of a doctor act so criminally negligent with Michael's life that he ends up killing him... then receives such a pitiful sentence.
"Dr Conrad Murray [should have been] charged with, and convicted of, second-degree murder and sent down for decades. A life incarcerated for the life lost because of his reckless choices, inept skills and breathtaking disregard of the human life in his solo care.
"As someone who sat through the evidence at trial before Murray was found guilty of involuntary manslaughter, I know there was enough legal justification to charge this case as second-degree murder."
Jermaine added that he "felt more like shrugging [his] shoulders than punching the air" after the verdict, due to LA district attorneys choosing the "safer option" of an involuntary manslaughter charge.
The 56-year-old did say that he was happy Judge Michael Pastor had ruled out the defence's claim that Michael administered the fatal overdose of propofol himself.
"That lie was sent to jail with the rest of Murray's lies," he said. "I just hope that for every long day that Murray does serve in jail, he is haunted by what he's done in the same way we've been haunted by what he didn't do - keep Michael healthy and alive.
"Propofol is like a gun - safe in the right hands but in the wrong hands, it's deadly. Michael placed his life in Murray's wrong hands."
Jermaine further suggested that Michael had been denied a "new, exciting future" due to Murray's failure to follow standard medical procedure.
"Had Murray monitored him, instead of wandering off to ring his girlfriends, he'd have seen that Michael had stopped breathing," he argued.
"Had he had the standard life-saving equipment and rang 911 and not stalled for 15 inexplicable minutes, there was always a real chance of life. Had he not kept hidden from paramedics the vital fact he'd administered propofol. Had he been a trained professional who knew what he was doing, Michael would still be alive today. I remain haunted by the endless list of 'Had he done this...'"
Michael and Jermaine's mother Katherine Jackson has said that Murray's sentencing is "not enough for someone's life".