A disgruntled customer being eyed as a “person of interest” in the knife slaying of the married shopkeepers known to perform “religious acts” in their Brooklyn shop was enraged — possibly because of an “occult service” gone “bad,” a police source said.

Stephenson Bonaparte, 65, and his wife, Hazel Brown, 59, were ambushed outside their Prospect-Lefferts Gardens home last week after leaving their business, King Solomon Religious Store.

Brown was known to perform “anything from readings to hexes,” according to the source.

Whatever Brown might have done for the customer, “it went bad and she wasn’t taking his calls,” the source continued, describing the rite as “some kind of occult service.”

Bonaparte was found with multiple stab wounds to his neck and the back of his head and a cut to the chest, while his wife was found inside her Winthrop Street home with cuts to her neck and torso, police said.

Bonaparte died at Kings County Hospital and Brown was pronounced dead at the scene.

One former customer, who declined to be named, insisted Saturday that the couple “walked in the light.”

“I never thought of them as the type of people to provide a hex. If anything they would provide protection against a hex,” said the person, who called the crime “satanic” and “evil.”

The pair performed spiritual readings and counseling, the customer added.