The crime was attempted murder. After a Long Long Island man allegedly stabbed his wife then tried to kill himself, their home resembled the aftermath of a horror film.

“Blood was everywhere,” Victoria Vallone, operations director with Bio Recovery, a New York-based company that cleans up death scenes, told The Post. “When people survive an attempted murder, they run all around the house.”

By the time Vallone’s crew rolled in — referred, as usual, by an insurance company — both parties had been taken to the hospital by EMS. But plenty of blood lingered.

“I don’t ask for too many details,” Vallone said. “I just assure relatives that we will go immediately and take care of it. We arrive in hazmat suits and remove all the biological material.

“We use an ATP monitor, which measures bacteria on direct surfaces — blood or bio material might not be visible to the eye but it needs to be cleaned. We remove carpeting. [In the above instance] a lot of the floors had tiling, which is good for keeping blood from seeping through. Wood floors can have cracks that allow the blood to go deeper and deeper.”

With murders and suicides surging in the United States — homicides rose a record-setting 30 percent in 2020 and have not abated — clean-up posses are busy.

“We’re seeing more suicides than we ever have,” Andrew Danilack, owner of northern New Jersey’s Spaulding Decon crime-scene clean-up franchise, told The Post. “They are generally older males, with the use of a shotgun or rope. A shotgun [suicide] is the hardest to clean up.”

Danilack recalls an incident from just before Christmas when the 30-something son of elderly parents shot himself in the basement of their home. As is the norm, a crew of crime-scene cleaners arrived in hazmat gear and employed proprietary cleaning products.

“We had to pick up a piece of the individual’s head and bone fragments from behind a storage box,” he recalled. “The floor was concrete. We cleaned it and sanded it and sealed it so that odors and stains stayed inside. A HEPA air scrubber vents everything out and filters the room.”

Companies generally charge around $5,000 for such services.

While it might generate bank for Vallone and her comrades, the rising rate of violent death leaves her chilled.

“It’s terrible,” she said. “We deal with families when [the bloodshed] just happened. We get there within an hour. It’s fresh and sensitive and people are crying, but the cleaning has to be dealt with by a licensed company. The last thing we want to do is allow the family members to do it themselves. It’s illegal for unlicensed people to dispose of regulated medical waste — there can be dangerous drugs like fentanyl or HIV in the blood — and it is not the way they want to remember loved ones.”

Concurred Danilack: “You walk inside and have immediate sympathy for the family.”

When absolutely necessary, Vallone said, “we do demolition. We get all biohazard material out of there, even if we have to knock down walls. When a body decomposes on the floor, you can smell it down the block. All the gasses are out. [In those instances,] the floor needs to be removed with power tools.”

As far as their own queasiness over all of this — “We keep puke buckets outside,” said Vallone, “and might change [blood-soaked] hazmat suits six times” over the course of a job — cleaners learn to get beyond the gore and remain strong for the clients who need them.

But it takes some getting used to. Vallone (who now mostly handles things from the office) remembers early jobs where she was “getting emotional, [while] my colleagues had ear buds in and stayed completely focused.”

Formerly employed in the production department of J.Crew, she recalled her first crime scene: “A son slit his mother’s throat in the kitchen, dragged her through the house to the bathtub and then turned himself in. There was biohazard and blood through the home.”

In another job, Vallone said, an elderly woman had fallen onto her white shag-carpeting with a broken hip. She laid there for days, unable to get up — and then her dog got hungry.

“The dog was eating at her,” Vallone remembered. “He dragged around pieces of her arteries. The woman passed away in the hospital. I don’t know what happened to the dog.”

Still, seasoned cleanup crews remain cognizant of the job that needs to be done and the difficulties endured by surviving relatives.

“Most of the time, we are helping people who are crying and going through the worst experiences of their lives,” said Vallone. “But this has to be dealt with, and we are there for them.”

Before elbow grease gets applied, she added, “I reassure [clients] that I am sorry about everything.”

Danilack explained that he works to keep customers, particularly those dealing with the most unsettling situations, as assured as they can be under the circumstances. “When there is a big domestic abuse or suicide, I go personally and talk to the family to make sure that they are comforted,” he said.

Most importantly, as Vallone put it, crime-scene cleaners ultimately foster a shortcut of closure: “We leave the place as if it never happened.”