Police identified the victim as Enrique Hernandez, 43, who had chop wounds on his neck, head and right leg.
Maria Hernandez, 33, of Idaho, and her brother, Hector Gutierrez, 22, of California, will now face charges of murder with a deadly weapon and conspiracy to commit murder, authorities said.
According to a Las Vegas police report, the sister wired $800 from a Walmart in Burley, Idaho, to her brother in Visalia, California, which Gutierrez said was for his trip to Las Vegas to carry out the murder plot. The woman said it was to pay for his living expenses.
The woman originally called in the fatal incident around 2:30 a.m. Monday as a carjacking. She was found at the scene with her husband dead, telling police the couple stopped on the side of the road to check on the van that they were driving. A stranger appeared, she said, and stabbed her husband and then took off with the vehicle.
The couple, who have four children, drove from Idaho for the holiday weekend, visiting family and attending a quinceañera celebration, according to the police report. On Sunday night, they left their children with a relative in the suburbs and met up with her brother at La Casona Bar and Grill, a Mexican-style bar, for drinks and dancing.
Police said the van was stopped that night about three miles away from the bar by an officer less than an hour before the attack because the headlights weren't on. The woman was allowed to drive off with her husband and brother inside.
Just before the bloody van was later found about 10 miles away from scene of the attack around 7:30 a.m., Gutierrez was reported to be at a Las Vegas hospital with a stab wound that he said came from a robbery. Meanwhile, authorities also followed a half-mile long trail of blood from the van that led to a Ford Mustang registered to Gutierrez. It was parked in the La Casona Bar and Grill's lot, police said.
The man later recanted his story, saying his sister had asked him to kill and he felt obligated to help her. The husband had discovered his wife had an affair, hired someone to beat up the boyfriend and threatened to take the children away, according to the police report.
That night, his sister showed him a hatchet hidden in the van. On his sister's call, Gutierrez said he struck his brother-in-law at least five times, including in the back of the head, as the man was checking on the van's engine. The man fought back despite being held back by his wife and stabbed Gutierrez with a knife. Another sister of Gutierrez had reported the stabbing, which sent the California man to the hospital.
The wife also recanted her story, saying her husband was abusive but that she had changed her mind on the fatal attack. The murder was supposed to happen the day before, after the family party, but she signaled against it to her brother, hugging her husband and saying she loved him, according to police.
The woman also said she tried to save her husband by grabbing both his arms to pull him away during attack the next day, but police say it appears she actually held him down as her brother chopped at his neck.
A listed telephone number or an attorney for Hernandez and Gutierrez couldn't be found to seek comment on the charges.
Copyright 2015 The Associated Press modified.