The owner of one of the country’s largest maraschino cherry companies fatally shot himself Tuesday as authorities raided his Brooklyn factory — a suspected massive drug front.

Dell’s Maraschino Cherries owner Arthur Mondella, 57, stood by and nervously watched as authorities spotted suspicious shelving in a storage room at his Red Hook facility — then opened up a door to the false wall behind it and the smell of weed wafted out, law enforcement sources said.

Mondella immediately “asked to use the bathroom, he went in the bathroom, and, ‘Boom,’ ” a source said.

Before shooting himself once in the head, Mondella told his sister, “Take care of my kids,” sources said.

Investigators later found three large bags of pot stashed behind the fake wall at the landmark business, which Mondella’s grandfather started.

He is suspected of using part of the factory as a grow house, sources said.

Mondella had been trying to reinvigorate his cherry business at the 175 Dikeman St. site, which sells to big chain restaurants such as Red Lobster, Buffalo Wild Wings and TGI Friday.

The company had recently become infamous with locals for turning sugar-addicted neighborhood bees red after they sipped on the syrupy sweet confection.

Authorities wanted to get a warrant to search the place after getting tipped off that it was a front for a marijuana business, but when they couldn’t, they decided to try to do an end run through the Department of Environmental Protection, sources said.

Investigators from the Brooklyn District Attorney’s Office and the DEP were technically searching the place for possible violations involving the dumping of waste when Mondella killed himself, sources said.

Mondella started out cooperative and calm during the several-hours-long search — until officials reached a room storing covered-up vintage vehicles, including a Rolls-Royce, a Porsche and a Harley-Davidson motorcycle.

There, they found the weird shelving and magnetically operated secret compartment behind it in the wall.

Behind the secret compartment, investigators discovered an entrance to a dug-out basement filled with three bags of marijuana.

“As soon as that door cracked, the aroma of marijuana was overwhelming,” the source said. “It looks like a cave, like they dug it out on their own.”

After Mondella shot himself with his .357 Magnum handgun in his personal bathroom and EMS was called around 1 p.m., authorities also recovered “hundreds of thousands of dollars” from the facility.

“Poor guy, in this day and age, you can do no jail time for marijuana,” a law enforcement source said. “I don’t know why he would do that, unless there’s something worse down there.”

Sources said investigators knew Mondella had a gun permit and should’ve asked him to hand over any weapons.

“If someone finds out that he had the gun on his belt and nobody took it from him, somebody’s got a problem,” a source said.

Poor guy, in this day and age, you can do no jail time for marijuana. - Law enforcement source

Investigators also found generators inside the factory as well as cameras in “every little nook and crevice,” the source said. The building was outfitted with barbed wire and motion detector lights.

“All that points to guilt — you’re not protecting your cherries,” the source said. “He’s probably growing.”

The source added that before the bust, Mondella was “very paranoid” and “loved cocaine.” One neighbor said she always smelled weed on Coffey Street.

Mondella’s ex-wife, Yevgeniya, was devastated by the news and said she’d only known him to be a casual pot smoker.

“His sister called me crying, saying that Arthur is dead,” she told The Post. “I’ve been 100 percent supported by him. I have no idea what I’m going to do now at this point.”

The couple shares a 5-year-old daughter named Antoinette — but Yevgeniya said he kept his work and home life very private.

The probe kicked off when Brooklyn DA detective investigators got a tip from a confidential informant in 2013 that the factory was a front for a marijuana operation.

Investigators kept close watch over the business for about six months — but couldn’t figure out if pot was being grown inside.

Finally, they used environmental agencies to secure search warrants.

“We figured one way or another, that would get us in there and then we’d find the marijuana,” a law enforcement source said.

The city put traps in the sewers that determined they were definitely dumping waste.

That allowed investigators from the Brooklyn DA’s office and environmental agencies to search the place Tuesday.

A Brooklyn district attorney’s spokeswoman declined to comment.

Additional reporting by Frank Rosario and Danika Fears