The little girl apparently told her grandparents, who lived upstairs, that James Cox had killed Massiel Deoleo, 34, of Mahwah, in the downstairs apartment of the family's 6th Street home sometime Friday night.
“Daddy killed Mommy,” she told them, but said Cox had assured her that it was only a nightmare, responders said.
Police got the girl and the grandparents out of the residence during Saturday’s prolonged standoff.
After nearly eight hours of negotiations failed to remove Cox, water was cut to the home and a SWAT team fired tear gas cannisters into every window in and around his apartment.
Members of the the tactical team then discharged a flash-bang to disorient him while forcing their way in.
"As soon as they made entry, they heard a single gunshot," an investigator told Daily Voice.
They found Cox's body and then Deoleo's, he said.
Deoleo had told her mother that she was going to Cox's apartment Friday night to collect some things and see her daughter, investigators said.
The couple went to dinner at Segovia Restaurant in Moonachie and were seen outside the apartment -- with their daughter -- as Cox walked his dog between 10 and 10:30 p.m., they said.
A friend also said he'd texted Cox and nothing seemed amiss.
Sometime later, the couple argued over Deoloe's use of the phone, multiple law enforcement sources said.
Following the mother of three into a bedroom, Cox shot her point-blank in the chest with a 9mm handgun, they said.
Concern for Deoleo’s welfare began when she didn’t show up for work at a local Chipotle on Saturday, a law enforcement source said.
Shortly before noon, a family member called Carlstadt police to report the Yonkers native missing, Bergen County Prosecutor Mark Musella said. She was last seen with Cox, he said.
Another family member called Mahwah police minutes later and asked them to do a welfare check at her apartment, the prosecutor said.
Township police found Deoleo’s cellphone, among other items, outside the Belgrove Drive apartment off Franklin Turnpike near Route 17, multiple law enforcement sources told Daily Voice.
Investigators believe Cox planted the items there after killing Deoleo.
Carlstadt police immediately went to the home off Berry Street where Cox lived with their daughter.
The situation instantly escalated when he pulled a semi-automatic handgun and pointed it at himself, Bergen County Prosecutor Mark Musella said.
Cox “said he was not going to shoot officers but was going to take his own life,” the prosecutor said.
Officers got the girl and her grandparents out safely, then called for reinforcements, including a Bergen County Regional SWAT Team and a county crisis negotiation unit, they said.
Carlstadt police also urged all residents on 6th and 7th streets between Division and Passaic avenues to shelter in place.
Authorities strongly suspected that Deoleo was in the apartment. But they had to proceed cautiously.
They reviewed area surveillance video from various locations in Carlstadt and Mahwah, checked Cox’s car and even brought in a K-9 unit to try and track her scent outside the home.
Cox’s estranged brother, an off-duty borough police lieutenant, arrived and offered whatever help he could while acknowledging there wasn’t much he could do.
Carlstadt Police Chief Thomas Berta also brought attorney Richard Potter of Hackensack, who had recently represented Cox.
Borough police who'd defused previous domestic incidents at the house were able to talk with Cox.
Police Officer Jason Columbo, in particular, connected with him – and even had someone get the gunman some McDonald’s.
County negotiators then “spent numerous hours attempting to resolve the situation peacefully,” said Musella, the prosecutor.
Those who hold police at bay in standoffs are always reminded that surrendering without incident works in their favor when they’re eventually sentenced. Any other outcome is guaranteed to be tragic.
Cox was given several opportunities to come out unarmed and end the standoff, authorities said.
He was reluctant.
As a convicted felon, Cox knew he was prohibited from having a gun – which meant a certain return to prison.
Cox had kidnapped his then-ex-girlfriend at knifepoint from her Parsippany home in July 2000. He drove the 20-year-old victim around for hours in a Chevy Blazer -- repeatedly asking her why she broke up with him – before raping her behind an industrial building in Carlstadt.
Cox forced the victim back into the Blazer, but she jumped out and fled while it was moving. She was later treated for a slash wound on her chest.
Cox pleaded guilty to first-degree aggravated sexual assault and served more than seven years in state prison before being released as a Megan’s Law Tier 2 offender, records show.
Around 6:30 p.m. Saturday, the SWAT team was ordered to enter his apartment.
“We need to know whether she's in there," a law enforcement official told Daily Voice at the time.
Utilities were cut off before the SWAT team fired in several 15mm rounds of tear gas, frightening neighbors who assumed they'd heard gunshots.
Several more volleys followed – well over a dozen cannisters in all -- they said.
Finally, the SWAT team burst in around 8 p.m.
A GoFundMe campaign was launched for the slain woman's funeral and care for her children. Nearly $15,000 had been raised as of Monday morning.
"My dear friend lost her sister Massiel Deoleo, her ex husband killed her and then killed himself," Yessenia Torres of New York wrote. "We are asking for help to cover funeral cost and after care for her 3 kids Janhel 15 years old, Bella 12 years old and Penelope 5 years old. Please pray for her family during this difficult time. No donation is too small anything at all would be greatly appreciated. If you can’t donate we would just ask that you share this page to show your support."
TO DONATE: Massiel Funeral cost (GoFundMe)
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