The billionaire husband and wife found hanging side by side in their posh Toronto home last month were murdered, according to a bombshell report citing a team of private investigators Saturday.

Multiple killers played a role in the deaths of Barry and Honey Sherman — contrary to the widely circulated murder-suicide theory initially leaked by law enforcement, sources told CBC News, citing a parallel probe by a team of investigators hired by the couple’s family.

A real estate agent who was selling the $5.4 million home had discovered pharmaceutical mogul Barry, 75, and Honey, 70, dead on Dec. 15.

There was no evidence of forced entry into the home.

Both husband and wife were hanging from a railing alongside the basement lap pool; initial autopsy results revealed both had died from “ligature neck compression.”

The private eyes, among them a number of ex-Toronto homicide detectives, are now painting a more complete picture of the death scene — and it points to a double murder after an extended struggle, likely two days before the bodies were discovered, CBC said.

Both Barry and Honey indeed had leather belts around their necks that were also knotted around the pool’s handrail, the CBC said, according to a source intimate with the private eyes’ investigation. But both bodies were in an upright, seated position on the floor near the pool.

Honey likely struggled before her death.

“She had cuts on her lip and nose, and was sitting in a pool of her own blood when she was discovered,” the CBC wrote.

“However, there was comparatively little blood apparent on her upper-body clothing, suggesting that she had been face-down on the tile, bleeding, for some time before being bound to the handrail in an upright position,” the CBC wrote.

Tellingly, the wrists of both Honey and Barry showed marks indicating they had at one point been bound together, according to the CBC’s source.

Whoever the killers were — and the private eyes believe it would have taken more than one — they took whatever was used to bind the couple’s wrists with them when they left the house, the source told CBC.

“Their bodies were otherwise limp and their arms unbound when they were discovered,” the source said.

The initial murder-suicide theory has outraged the Shermans’ friends, neighbors and family members, including their four adult children.

The couple had faced some financial woes, and Barry was involved in fighting dozens of lawsuits connected with the family fortune and his former pharmaceutical company, Apotex.

But family members pointed to the couple’s plans to travel to their Miami condo, and their delight in a recent grandchild.