Story highlights Nicola "Coco" Campolongo was shot and killed last week

His grandfather and grandfather's companion were also killed

The boy's death has shocked the country, even catching the attention of Pope Francis

Mafia killings don't typically shock Italians -- as disturbing as the occasional hit may be, the tragedy usually affects only friends and families of the victims.

But a coldblooded, point-blank killing this month in southern Italy has a nation grieving -- for a 3-year-old child.

Nicola "Coco" Campolongo was shot in the head along with his grandfather, Giuseppe Iannicelli, and his grandfather's 27-year-old companion -- victims of an apparent mob hit over money.

Their bodies were found January 19 in a burned-out Fiat Punto on the outskirts of Cosenza, in southern Italy's Calabria region. Iannicelli, who was serving a drug-related sentence on house arrest, appeared to be the target of the hit.

"In all my years investigating organized crime murders, none has been as horrific as this one," lead prosecutor Franco Giacomantonio told CNN. "It is unimaginable that a child can be made to pay for the crimes of his parents."

The killing even caught the attention of Pope Francis, who called Coco's death "unprecedented." He asked worshippers at his Sunday address to say a prayer for Coco and called on the boy's killers to repent for their crimes.

Coco's 24-year-old mother, Antonia Iannicelli, didn't attend her son's funeral. She's serving a four-year jail sentence for the possession and sale of drugs. Police feared members of the powerful 'Ndrangheta crime organization -- believed to be behind the killings -- would target Iannicelli if she attended.

Her two other children, ages 4 and 5, were moved to protective custody in another region of Italy. Iannicelli will be allowed to serve out the rest of her sentence on house arrest with her surviving children.

The killing of such a young child has sparked debate in Italy about how to protect children growing up in the shadow of the country's crime syndicates in the impoverished south. Coco was just an infant when his mother began serving her jail sentence.

On Tuesday, Francesco Talarico, head of the regional government in Calabria, wrote a letter to the president of Italy's national observatory of the rights of minors, urging the group to "lift the veil of silence" that often accompanies mafia crimes, and to "seriously investigate what can be done to protect the future of at-risk children like Coco."

Coco's mother was already serving her second prison term for drug crimes tied to 'Ndrangheta -- one of the most powerful organized crime syndicates in the world, according to Francesco Forgione, head of Italy's Parliamentary anti-Mafia Commission.

"Coco's mother is the first victim of the system," Talarico told CNN. "Her son had little chance to escape that life."

In the wake of Coco's killing, Interior Minister Alfano Angelino and National Police Chief Alessandro Pansa signed an emergency protocol in the child's name to ensure the protection of children's rights.

"We need ... to make sure the protocol does not forget children who are growing up in vulnerable situations outside the law, who may be victims or witnesses to crimes. We need to make sure Coco is the last child ever killed like this," Pansa said.

No suspects have been named in the triple homicide, but Giacomantonio believes it is likely connected to the region's drug trade.