Comic book writer Gerry Conway created the Punisher, a new bad guy for Spider-Man to fight, way back in 1974. The character was a Vietnam veteran whose family was murdered, and he subsequently goes insane and turns into a crazed vigilante. He kills all lawbreakers regardless of what law they break; if I remember correctly (I collected comics as a kid), this is illustrated by him shooting someone for driving through a red light.

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Sadly, the Punisher's symbol has been appropriated by a handful of America's police officers:

This has been going on for a while, and last year Conway told Syfy Wire what he thought of the practice:

"It's disturbing whenever I see authority figures embracing Punisher iconography because the Punisher represents a failure of the Justice system. He's supposed to indict the collapse of social moral authority and the reality [that] some people can't depend on institutions like the police or the military to act in a just and capable way.

The vigilante anti-hero is fundamentally a critique of the justice system, an example of social failure, so when cops put Punisher skulls on their cars or members of the military wear Punisher skull patches, they're basically sides with an enemy of the system. They are embracing an outlaw mentality. Whether you think the Punisher is justified or not, whether you admire his code of ethics, he is an outlaw. He is a criminal. Police should not be embracing a criminal as their symbol.

Following the recent social unrest, Conway resolved to do something about it:

Responses came in almost immediately, and just days later, Conway had set up BLM - Skulls for Justice.

Each T-shirt design is its own mini-fundraising campaign that runs until June 30th, and 100% of the proceeds go to Black Lives Matter.