Ex-boyfriend suspected in murder-suicide; 6 dead

A manhunt for a gunman who allegedly killed five people at a birthday party hosted by his estranged girlfriend ended in Rancho Cucamonga on Sunday, when the suspect apparently shot himself.

The apparent suicide came after he dropped off his two young children, whom he had abducted from the shooting scene in Lake Havasu City in Arizona, according to authorities.

One of the victims, identified as the mother of the children, had obtained a restraining order against the alleged gunman, Brian Diez, earlier this year, according to Sgt. Joe Harrold of the Lake Havasu City Police.

Diez, 26, was prohibited from contacting Deborah Langstaff, 23, and their two young children, Harrold said. A misdemeanor domestic violence charge was also pending against Diez in connection with an alleged slapping incident involving his infant son, Harrold said. Diez had pleaded not guilty.

The bloodshed began shortly before midnight Saturday. Diez allegedly burst into Langstaff’s home in the 300 block of Opossum Drive in Lake Havasu City, where she was holding a birthday party for her new boyfriend, police said.

Diez allegedly killed Langstaff and three others at the home and wounded two partygoers, one of whom later died at the hospital. Diez then fled with his two children, a 13-month-old boy and 4-year-old girl, and drove to a relative’s home in Rancho Cucamonga. He left the children there before apparently shooting himself, officials said.

Langstaff, a nursing unit manager at Havasu Regional Medical Center, and Diez had separated, Langstaff’s grandfather told The Times in a brief phone conversation.

Neighbors in the tract of single-story desert homes with rock gardens said it appeared Diez moved out at least a month ago. The couple had lived in the home about a year and mostly kept to themselves, and there had been no outward signs of strife, the neighbors said.

“I don’t understand this,” said neighbor Teresa Williams, whose bedroom faces the Langstaff residence. “There’s never been any chaos … never been a sign that anything was amiss.”

Langstaff had invited friends to celebrate the 24th birthday of her boyfriend, Primo Verdone, police said. Verdone was among the victims pronounced dead at the scene along with Langstaff, Ashley Nyland, 20, and Russell Nyland, 42.

Two others, Brock Kelson, 20, and Deborah Nyland, 44, were taken to Sunrise Medical Center in Las Vegas, where Kelson died. Deborah Nyland was in intensive care with a good prognosis, Harrold said.

After issuing an Amber Alert early Sunday for a child abduction, authorities located Diez’s vehicle at a residence in the 11900 block of Rue Way in Rancho Cucamonga, said Charlie Cassens, a Lake Havasu City spokesman. The circumstances of Diez’s apparent suicide were unclear Sunday night. Relatives and neighbors declined to comment.

The two children, Kaia and Cole, were found safe at the Rue Way residence, Cassens said.

Public records show Diez had an address in Glendora and held jobs in Lake Havasu City, including operating Redline Speed & Marine, a retail business that sells boat parts and accessories.

A man at the Glendora address who identified himself as Diez’s father declined to comment Sunday.

At the Lake Havasu City hospital where Langstaff worked, colleagues were trying to cope with the deaths. She had worked at the medical center about four years and had been on duty Friday, said Sheena Benson, a hospital spokesperson.

“She was well liked. She was very, very professional,” she said. “And definitely seemed like a very happy person.”

ashley.powers@latimes.com

kurt.streeter@latimes.com

corina.knoll@latimes.com

Times staff writer Rich Connell contributed to this story.