Ex-cop says he shot ATF agent at LI drugstore

ATF Agent John Capano.

The retired Nassau County cop who fatally shot an ATF agent claims he yelled out, “Who’s the good guy?” during the struggle outside a Long Island pharmacy — and fired his gun only because he thought the federal agent was a thug who was shooting at him, The Post has learned.

Then, realizing he shot a good Samaritan, former Lt. Chris Geraghty, 54, desperately tried to save Agent John Capano’s life by applying pressure to stop the bleeding from a wound that pierced the hero’s heart, a source said.

Geraghty defended his actions to detectives probing the Saturday friendly-fire tragedy that left Capano, 51, and pill-popping jailbird James McGoey, 43, dead.

Geraghty told cops a woman ran into the Seaford Deli — where he was working and off-duty NYPD cop Joseph Abria was having lunch — and yelled that a gunman was holding up Charlie’s Family Pharmacy two doors away.

As the lawmen ran out the door, Geraghty’s wife, who also worked at the deli, yelled to the pair to alert them, “He’s NYC police; he’s retired Nassau!”

The men saw ­Capano, a married father of two teens, and McGoey grappling on the ground for Capano’s gun.

Geraghty told cops he and Abria both yelled, “Police! Put the gun down!” the source said.

Geraghty said he tried to separate the two, grabbing Capano and yelling: “Who’s the good guy? Who’s the good guy?”

Capano reportedly didn’t answer.

A moment later, the agent wrestled the gun from McGoey — but as the agent’s arm jerked around, he squeezed off a shot that whizzed by the ex-cop’s head, according to Geraghty.

Thinking Capano was shooting at him, Geraghty fired back, ­fatally wounding the 23-year veteran agent.

McGoey then raised Capano’s gun, so Abria shot him dead, Geraghty told cops, the source said.

A drugstore employee then ran into the street and, seeing ­Capano lying on the ground wounded, screamed: “John!”

Only then did Geraghty realize Capano was a Samaritan, and attempted CPR. He said he didn’t learn Capano was an agent until a day later.

Brian Davis, Geraghty’s lawyer, would only say, “Chris Geraghty is devastated. He wants to express his deepest condolences to the Capano family.”