SAN RAMON -- The grandparents of two young boys -- left home alone while their parents partied over New Year's in Las Vegas -- asked Contra Costa County officials Thursday for full custody of the children in a case that is drawing national attention.

Donald and Libbey Holden told court officials during a morning conference that they wanted the children to live with them in Manteca. A hearing on the petition was schedule for Thursday afternoon.

The couple had a chance encounter with the boy's father -- Jacob Calero, who has been arrested on child endangerment charges -- at the courthouse in the morning.

"I kinda of felt like...I pitied him because you know as my husband said we've had some good times," Libbey Holden said. "When I saw him (dressed in a jail jumpsuit) my heart broke for him because I'm not used to seeing him in that condition."

Calero, 39, and his second wife, Michelle De La Vega, 32, left Calero's sons -- Joshua, 9, and Jason, 5 -- at their San Ramon home early Friday while the newlyweds headed out of town for a five-day trip.

Authorities said the couple found a dog sitter for their new puppies, but left their son home to care for his younger autistic brother while they celebrated the new year in Las Vegas. They were arrested Wednesday when they arrived at Oakland International Airport.

The children's mother and Holden's daughter, Cristina Calero, died of breast cancer in 2003 and Jacob Calero married De La Vega last year.

Joshua, interviewed Wednesday at his grandmother's apartment in Manteca, said his dad and stepmother got each other puppies for Christmas, and went so far as to bring the pug and the poodle-Maltese mix to De La Vega's mother before leaving town.

"I thought they loved them more than us," the boy said.

Libbey Holden said she called police after she suspected the couple had left the children behind.

"I had big concerns," Holden said Wednesday, sitting in her apartment filled with family pictures, including smiling portraits of her late daughter. "These kids are helpless."

Police said they found the children asleep in their beds Saturday night, a day after being left alone. A gas fireplace was turned on, but they found nothing out of the ordinary.

"It appears that the food and the environment were set up for them to be alone," San Ramon Police Sgt. Brian Kalinowski said.

The older boy said he was instructed to not answer the front door, so officers had to use a ladder to enter the home through an unlocked sliding glass door on a second-floor balcony.

Kalinowski said Wednesday that neighbors reported hearing the younger boy screaming "Help Me! Help Me!" from inside the family's garage Saturday. They went over to retrieve the boy and, finding no one home, left a note explaining he was at their house. When the older boy returned after about an hour, he picked up his brother and took him back home.

Kalinowski said arresting the husband and wife on suspicion of two felony counts each of child endangerment was a "no-brainer." They were being held at the Martinez jail on $200,000 bail each.

Joshua, who said he was glad his dad was arrested, explained that he and his brother ate cereal for breakfast and cooked frozen dinners in the microwave for lunch and dinner. He said his dad and stepmother left while they were asleep. They had asked him to watch his younger brother, but didn't tell him where they were staying, he said.

"They shouldn't leave us alone," Joshua said, sitting in the living room of his grandmother's apartment. "I didn't know who I could call in an emergency. Even if I called my father, he's far away, so there wouldn't be much he could do."

Holden said she tried calling Calero, but couldn't reach him. Worried, she consulted friends, and finally decided to call authorities.

Officers began calling Calero's cell phone Saturday, but he didn't call back until Tuesday.

"It seems to me that, as a parent, you would take a plane, train or automobile to come back to your kids as soon as possible," Kalinowski said. "We get the sense that they felt no urgency for them to return home."

They flew from Las Vegas early Wednesday and were arrested at Oakland International Airport about 11 a.m. Both have requested lawyers and have refused to talk to police, Kalinowski said. Felony child endangerment carries a maximum sentence of six years in prison.

Joshua said it wasn't the first time he and his brother were left home alone. Last fall, his dad and stepmother kept him out of school for a week so he could baby sit his brother while they went away.

Calero is a plumber and De La Vega works in a dental office, police said.