An acquaintance of the Butwin family told police on Monday that he was concerned about them after receiving a note from James Butwin with instructions on how to operate his construction business without him, Tempe police Sgt. Jeff Glover said.
Investigators went to the Butwin home and found "suspicious and concerning" evidence, but not the Butwins, and began treating the case as a murder-suicide. The family's white Ford Expedition also was gone.
Glover declined to specify what the evidence was but said no murder weapon was found in the home.
Meanwhile, the Pinal County Sheriff's Office was investigating the discovery of five bodies found burned beyond recognition in a white Ford Expedition in the desert 35 miles south of Phoenix on Saturday morning.
Glover said that the sheriff's office has since notified them that the SUV in the desert was registered to the Butwin family's home.
He said that although they can't be entirely certain that the Butwins are the same five people found in the burning SUV, investigators are so sure that they're dead that they aren't looking for them and believe there are no outstanding suspects.
Glover said that James and his wife Yafit Butwin were experiencing financial difficulties, and court records show that Yafit filed for divorce in September and that the process was ongoing.
Two of the couple's children were teenagers and one was a pre-teen, but Glover did not have their exact ages.
The five bodies found in the desert have not been positively identified because they were burned so badly beyond recognition, said Gregory Hess, chief medical examiner for Pima County.
He said the bodies could have included older children but not younger ones.
He said the office will have to use dental records to try to confirm the identities of the bodies.
Robert Kempton, a neighbor of the Butwins, told The Associated Press that the couple had confided in him about going through a divorce and that James Butwin was battling a brain tumor.
Kempton said that after chemotherapy, the tumor returned and that James said late last week that he was discouraged that treatment wasn't helping him.
He said the family had been planning a summer trip to Israel, Yafit Butwin's home country.
"I would have thought that they would have worked through this," Kempton said, referring to the divorce. "This is a big shock."
Kempton said that he and his wife moved into the quiet, middle-class neighborhood a few years after the Butwins, who he thinks have lived there about 12 years.
"From what we know them to be, this is totally unexpected to the point of almost being unbelievable," Kempton said. "We'll choose to remember them in the wonderful, positive light that we knew them."
Earlier Tuesday, the sheriff's office said they were also investigating the possibility that the burned bodies belonged to five men involved in illegal activities.
Sheriff's spokesman Tim Gaffney said a man who asked to remain anonymous called investigators Saturday and said that his brother-in-law was involved in illegal activity and feared that he could be among the dead. The man said his brother-in-law told him the night before the bodies were found that he was "going to Vekol Valley to make money" with four of his acquaintances.
The man told investigators that when he tried to call his brother-in-law and the other men on their cellphones, the calls all went straight to voicemail.
The men were last seen driving a Ford SUV, but detectives have been unable to talk to the tipster since Sunday.
The sheriff's office declined to answer any questions about the information in the news release or whether they thought one possibility was more likely than another.
Sheriff Paul Babeu said Monday that the location of the smoldering SUV in a known smuggling corridor and the nature of the crime itself had him all but certain that a violent smuggling cartel was responsible.
Babeu said that the burned car likely is the same car that a Border Patrol agent saw four hours earlier Saturday when it was still dark.
The agent saw a stopped white Ford Expedition and became suspicious, but when he approached, the vehicle fled and the agent lost it, Babeu said.
When the sun came up, the same agent saw car tracks in the area leading into the desert and shortly after, found a smoldering white Ford Expedition, Babeu said.
When the agent approached the car, he saw four burned bodies lying down in the cab of the vehicle, and one body in the back passenger seat; no one was in the driver's or front passenger's seat.