Jason Y. Cai, a 44-year-old software engineer, was arrested June 26 after authorities found 30-year-old Ying Deng, his wife of just six weeks, floating in the couple's backyard swimming pool.

Cai is being held without bail in the mental health ward of the county jail.

"We're shocked and disturbed by what happened in this little neighborhood. It's very sad," said Bertha Sullivan, who has lived on Kingsbury Court with her husband, Charles, for 40 years.

According to Terrance Helm, spokesman for the Santa Clara County Office of the Sheriff, Cai called the sheriff's department at 9:19 p.m. on June 25 to report his wife missing.

Responding deputies located Deng's body floating face down under the cover of the swimming pool. She was pronounced dead at the scene.

Santa Clara County sheriff's department homicide detectives and crime scene investigators were quickly called to the scene. After some investigation, Cai was arrested for murder.

According to Helm, one of the reasons for Cai's arrest is because of inconsistencies in his statements to investigators.

Cai stated that he saw his wife in their home when he returned from work at about 5 p.m. on June 25. For the next three hours, Cai said, he worked on his computer in the living room while his wife did house chores. At 8 p.m., Cai said, he became suspicious, as his wife had not prepared dinner.

Cai called 911 at 9:19 p.m.

Neighbor Charles Sullivan said he heard a loud noise on June 24 while he smoked a cigarette outside his home, which faces Cai's residence across the street.

"I thought they were having a party or something. I also wasn't sure if the noise came from Cai's home or the people who live behind him," he said.

Although Cai has lived in his home on Kingsbury Court for five years, he remains a stranger to neighbors, who describe him as a loner.

"The last time I talked to him was when he moved into his home five years ago with his ex-wife and their daughter. I went over there to welcome them to the neighborhood. He was very standoffish," Charles Sullivan said.

"We would wave when we saw them, but they'd never wave back or respond. They never talked to others here and just kept to themselves. I don't even know what his first wife looks like," Bertha Sullivan said.

Cai's ex-wife and daughter moved out of the residence after the couple divorced. Cai married Deng on May 13 after he met her in China and brought her to the United States on May 10.

"She seemed nice," Bertha said. "She was always working in their front yard. I was happy to see her cleaning up the yard. The weeds were knee-high before."

According to Sgt. Skip Shervington, community resources coordinator, the last homicide in Cupertino happened in 2001 at the Cupertino Village. A security guard was shot to death during a jewelry robbery.