Alvaro Camara and his two children.
SANTA ROSA (Debora Villalon/KTVU) -- Santa Rosa Police say a "volatile" custody situation ended with the double murder of two young children during an extended Father's Day weekend visit
After killing them, police said their father then ended his own life.
"I'm not quite sure what was going through his mind," Jessica Espada told KTVU, at the crime scene on Slater Street, near the Santa Rosa Junior College campus.
Espada identified her brother, Alvaro Botelho Camara, 40, as the man who is accused of killing 6-year-old Juliana Camara and 18-month-old Julian Camara,
Police would not say how the children were killed, but they said Camara hanged himself in a bedroom of his ground-floor apartment. .
Camara had the children at his apartment Sunday, as part of his custody agreement.
Espada came to the scene Monday, still absorbing what had happened.
"It just caught all of us by surprise, and it's very tragic," said Espada, "and we aren't sure why he would do such a thing."
"A beautiful little girl and a sweet little boy," neighbor Julia Poncia told KTVU, outside the small complex.
Residents had been getting to know the children, after Camara moved in a few months ago.
"He was great, he'd have the kids visit, and ride bikes, and he'd take them to the park," Poncia said sadly, "and so I don't know. You just never know about people."
"It's an absolute tragedy to see two young children lose their lives in a custody dispute," Santa Rosa Police Lt. John Cregan told KTVU.
Detectives were at the scene all day Monday, trying to determine a timeline, and a trigger for the sudden violence.
Camara was supposed to hand the kids over to his estranged wife at his apartment Sunday evening at 7 p.m.
No one answered her knock.
"Our preliminary investigation shows they did have a volatile arrangement following their separation," Cregan said, "and there have been heated verbal exchanges that we're aware of."
Still, there appeared to be no warning of the violence.
Camara's estranged wife lives outside city limits, so she reported that her kids were unaccounted for to the Sonoma County Sheriff's Department.
Deputies Sunday night found Camara's place dark and quiet as well, and figured he was extending his Father's Day visit with them.
They left, and returned Monday morning, with worried relatives.
Climbing through a bathroom window, they were able to find the bodies.
"They took off a screen on the window and were trying to go in there," described a neighbor who gave her name as Tanya.
She lives above the Camara unit, and thought the commotion at his door was odd, because she is convinced she heard him and his daughter speaking earlier in the day.
"I heard them talking this morning, about 7:30 or 8:00, what were they saying, I don't know but I could hear their voices."
Another neighbor said Camara had seemed nervous over the weekend.
"We've just noticed he was a little anxious the past couple of days," shared Carrie Buchholz, "and the police have been here off and on but he was always really good with the kids."
The couple had been together about eight years, and filed for divorce only a few months ago.
Police say it's too earlier to know if a more aggressive search for the children might have made a difference.
"We're stilll going to be exploring the timeline to determine when the children were last seen and when the tragedy occurred," Cregan said.