Everyone here has very good suggestions for how these people should be punished. I have one better, I believe, unfortunately part two of the punishment is not currently an option. I read science fiction, and in one story I read, wish I could remember the name and/or author, violent criminals were punished by enduring exactly, as forensically possible, what their victims endured. If the victim was shot five times in various parts of the body, they criminal would be shot in those same locations, without medical treatment. In this case, the boyfriend should endure 8 years of torture, and since the forensic evidence cannot recreate the crime exactly, he should endure random burning, being shot with a bb gun, and beaten every day for 8 years, one day for each of Gabriel's foreshortened life, including breaking a few bones occasionally.
As the mother did not, according to the article, engage in the abuse, but did nothing to stop it, she should be required to undergo the same punishment.
Since I am a jerk when it comes to bureaucrats and their apathy regarding the quality of service they provide, I think the failure of the CPS agent should result in his/her having to endure the same punishment. That person is as guilty as the mother for failure to do her job. That person was negligent and even the Director of DCFS said agents are not punished properly when their inaction or improper investigation results in death.
And not one of you bleeding heart liberals complain that is too harsh for him/her. That persons failure to do their duty resulted in the death of a child for whom numerous reports of abuse were made. The CPS agent's apathy in properly doing their job allowed this to happen; in my opinion they probably believe they are over-worked and underpaid.
And at the end, the mother and the boyfriend should DIE.
I like the mention of California CPS taking a child from the custody of parents who were concerned about their child and wanting a second opinion. I remember hearing that story and how much it pissed me off. Those on the left should really take that story and this one to heart. When the government has you under their control, they can do what they wish regardless of the consequences. You will have given up your liberty for lack of responsibility and the need to make decisions.
Although this has nothing to do with how I feel the mother and boyfriend should be punished, I mentioned that there was part of the punishment in the book that could not be implemented as yet. At the time of death of the prisoner his/her brain was preserved and dumped into a box that was placed inside of a robot shell. They were recruited for military purposes and under severe control at all time. In the story, each criminal remembered not only the crime they committed, but every detail of their punishment.
Either part of this type of punishment, separately or together, would probably have a dramatic effect on criminal activity, I would hope.