Just four hours after allegedly killing 24-year-old Alisha Canales-McGuire, a Washington teen filmed a video of himself fanning out over $2,000 in cash at his Spokane home.

You’ll “never guess what I did 4 this check,” the boy wrote in a caption on the Sep. 2017 video, according to a 22-page probable cause affidavit filed by the Snohomish County Sheriff’s Office Monday evening.

Authorities allege the then-19-year-old, along with a 16-year-old girl, were hired by a man to murder his ex-wife, Amanda Canales. But in a tragic case of mistaken identity, the teens instead gunned down Canales-McGuire, the intended victim’s little sister, according to the affidavit.

“She had been staying at her sister’s home and it is believed her sister, who was out of town at the time, was the intended target of the murder-for-hire by her ex-husband,” a spokesperson for the sheriff’s office said Tuesday.

The ex-husband, 31-year-old Kevin Lewis, and the hired killers, now 20 and 17, were arrested Monday night on charges of aggravated first-degree murder with a firearm and first-degree criminal conspiracy to commit murder, authorities said. Lewis, who is already in jail on 2018 assault charges, was also charged with solicitation to commit murder.

The 20-year-old and 17-year-old have not been publicly identified.

“It’s a relief to have the world know what my family and I have known the whole time,” Amanda Canales, who had three children with Lewis during their eight-year marriage, told The Daily Beast on Tuesday. “Now the world knows what kind of man Kevin Lewis is, finally.”

On Sept. 20, 2017, Canales-McGuire was babysitting her nephew and two nieces for her sister, who was on a business trip in New York, when the doorbell rang at around 1:55 a.m.

Trying not to wake up the children and their nanny, she opened the door quickly, the affidavit says. Canales-McGuire had little time to react: The young man came around the corner and began firing as soon as she opened the door, authorities said.

“The two drove from Spokane, where they were both living at the time of the murder, to Snohomish County,” authorities said. “Cell phone records put the phones of both suspects at locations consistent with traveling together and with the timing of the murder.”

Both teens repeatedly shot Canales-McGuire, never questioning whether she was their intended target, according to the affidavit.

“Patrol arrived on scene and found Alisha basically dead in the doorway of the home,” a spokesperson for the Snohomish County Sheriff’s Office told KING-TV. “We believed at the time even, that the intended victim was going to be the victim’s sister who had had a very difficult break up and rocky relationship with her ex-husband.”

Detectives believe the teens were initially approached by Lewis a few months before the slaying, at which point he allegedly offered them $2,400 to get his ex-wife “out of the way.”

During their 2017 divorce, Canales was granted full custody of their three children, and Lewis was required to pay the 31-year-old $800 per month in child support. The outcome enraged Lewis — who had recently been charged with assault for a November 2016 incident that landed his wife in the hospital — and he threatened to murder her if he didn’t get his children back, Canales said.

“He said, ‘Come back home or else I’m going to take you to court, and I’m going to get full custody, child support and alimony, and if I don’t get it I’m going to kill you,’” she told the Beast.

On the night of the murder, Lewis told investigators “he was home all night,” according to the court documents.

Investigators finally got a break in the murder case in 2018, when they received a tip that a girl had admitted at a party that she was hired to kill someone in Snohomish County.

“The female suspect allegedly bragged to several acquaintances that she’d been hired to kill someone,” the affidavit states.

The girl, who was just 16 at the time of the murder and had once dated Lewis’ cousin, allegedly claimed she and her accomplice were originally offered $10,000 by a “baby daddy” to kill a woman. According to the affidavit, the pair actually “negotiated the price from Kevin Lewis’ first offer of $1,500 to the final agreement of $2,400.”

The 20-year-old is currently being held in the Snohomish County jail on $5 million bail and the teen girl is being held in the Denney Juvenile Justice Center. It was not immediately clear whether they have attorneys.