Cannon Hinnant was gunned down in front of his sisters, aged 7 and 8, while playing outside their family home in North Carolina on August 9.
His tragic death has been seized on by detractors of the Black Lives Matter movement who claim Cannon's killing would have been treated differently if he was black.
Cannon's neighbour Darius Sessoms, who is black, has been arrested over the killing and Sessoms' parents have claimed their son had been suffering with drug and mental health issues.
The prison officer, Rome Smith, allegedly wrote on Facebook about Cannon's death blaming the boy's parents, which was screenshot and widely circulated.
"He should've ducked," Smith allegedly wrote. "Y'all always trying to sneak diss and discredit a black person being killed innocently by police. Blame cannon's parents for not watching him!!! F Y'ALL."
Smith's post sparked outrage and claims he was "obviously racist against caucasians", the New York Post reported.
In a statement to NJ.com, Smith's employer said he had been suspended and denounced the "shockingly insensitive and racist" comments.
"We will not tolerate County employees using social media to broadcast hateful messages," Cumberland County Freeholder Director Joseph Derella said.
"This is not who we are and we intend to pursue the strongest action available to us."
Cannon had been riding his bike outside his father Austin Hinnant's home when Sessoms allegedly walked up to him and shot him in the head.
"The first thing that went through my mind was maybe he just fell off his bike," Hinnant told local station WRAL.
"The closer I got to him, the more I realised it was something far more serious."
Sessoms was later arrested and has since been charged with first degree murder.
Hinnant said he had lived next door to Sessoms and his parents for eight years and there was no "bad blood whatsoever".
Sessoms' parents told AP they believe their son had been on drugs and experiencing hallucinations when Cannon was shot.
Hinnant told the Wilson Times he had been upset by social media reports that wrongly claimed race had been a factor in Cannon's death
"This is no racial issue," he said.
'STOP WEAPONISING THIS TRAGEDY'
Cannon's death began trending on social media earlier this month after several conservative commenters claimed his death had been overlooked because he was white and Sessoms was black.
However detractors pointed out that Cannon's death has been reported by most US American media outlets, slamming those who have "hijacked" his slaying for political purposes.
A GoFundMe page to raise money for Cannon's family has reached more than US$1.1 million, smashing its original target of US$5000.
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