The suspect who gunned down a Brooklyn bodega worker in a robbery gone wrong was a regular customer — and had come in just hours earlier for an egg sandwich, an NYPD source said Wednesday.

Fadhl Moosa was shot in the head and killed just after 7:30 p.m. Tuesday when the gunman went behind the counter of the bodega at 703 Flatbush Ave., police said.

The perp, who hasn’t been named but is described as emotionally disturbed, fired his gun after the clerk told him to get out from behind the counter, a source told The Post.

He had demanded money from Moosa just moments earlier, police said.

Deli workers didn’t think the gunman was a threat because he regularly comes in, the source said, adding that sometimes he pays for items and other times he doesn’t.

The suspect had come in earlier Tuesday to order an egg sandwich, according to the source.

He was wearing the same clothes when he returned that night when Moosa was shot dead.

Responding officers found Moosa behind the counter, lying face down in a pool of blood. He was pronounced dead at the scene, police said.

Mayor-elect Eric Adams visited the crime scene Wednesday with his incoming NYPD Commissioner Keechant Sewell.

“We are asking people to come forward with information. The detectives are here, they’re looking at the video, the footage to get this case closed. We want anyone who is responsible for a crime like this to be brought to justice,” Adams said.

“A young man is lost due to gun violence. We have been talking about the over-proliferation of guns in our community. After announcing the police commissioner, we wanted to come by here to show respect for the family. A son was murdered here in the city.”

Sewell, who will be the first female to take on the top NYPD job, called the deli shooting “totally unacceptable.”

Their visit came just hours after Sewell vowed to crack down on gun violence as she was officially announced as police commissioner.

The mayor-elect reaffirmed the need to bring back plainclothes officers to crack down on gun violence in the city.

“Within one year, you’re going to see real change in how we handle crime,” Adams said, adding that his approach would include partnerships with district attorneys, judges and crisis management teams to prevent crime in the first place.

Asked whether he and Sewell will continue to visit crime scenes when they take office on Jan. 1, Adams said: “You are going to see the most visible mayor in the history of New York.”

“I think it’s crucial that we come out here to this community … If the commissioner and the mayor fail to come here, we don’t come here and say to the people, ‘We are here with you,’ it sends the wrong message,” he said.

“We’re going to be visible in our community and make sure that people know we are here with you. You’re going to see us on the trains, on the streets, you’re going to see us in NYC Housing Authority — we will be visible together.”

Adams and Sewell were joined by local Assembly member Rodneyse Bichotte and incoming council member Rita Joseph.

“No one should be killed while trying to provide for their family. I’m heartbroken this morning as I stand here,” Joseph said.

“My heart goes out to the family who lost someone today who was just trying to earn a living.”

A relative at the scene who didn’t want to be named told The Post the victim was “a really good person.”

Denise Thomas, a local resident who frequents the deli regularly, said the victim’s family had been in Flatbush for decades.

“You could be short of change, they don’t care, they feeding you,” she said of the slain clerk and his family.

“When I heard, I melted. They need to clean up these streets.”