CONCORD -- A Virginia couple is flying here Tuesday to learn how the man's 86-year-old mother slipped out of her adult care home Sunday before being found dead at a nearby elementary school playground.

The family of Yolanda Membreno has questions about how her exit apparently went undetected, why it took nearly an hour for staff to call police and why they were told she had died in her bed peacefully.

"We were not told the horrible details about what was really going on until we had a coroner call us this morning and told us quite a different story," said a distraught Sabrina Sanchez, Membreno's daughter-in-law.

Caretakers at Julia's Home, 1020 Hampton Drive in Concord, noticed Membreno was missing about 4:30 p.m. Sunday and conducted a search of the neighborhood before calling police about 5:30 p.m. A police dog traced a scent to the playground of Fair Oaks Elementary School, where officers found Membreno's body at 7 p.m.

Julia's Home, a single-story home on a residential street with six beds, abuts the school, which is located in Pleasant Hill. The playground is about 100 yards from the home.

According to Membreno's family, the owner of the home contacted them about 10:30 p.m. Sunday and told them the woman died of a heart attack in her bed. The family said Julia's Home owner Roy Roberto backed away from those statements Monday morning.

On Monday, Roberto flatly denied saying any such thing to Membreno family members.

"I never said that she died in her bed at all," said Roberto. "I never used those words."

Roberto said he called the family Sunday to say Membreno had died. He said he gave no details because he was told police would do so.

"I have nothing to hide here," said Roberto. "I followed my procedures and protocols."

The coroner said a cause of death is unknown pending an autopsy Monday and that the results may take up to three months to process.

Foul play is not suspected, and it isn't known whether Sunday's high temperatures may have played a role in the woman's death.

Membreno, an Alzheimer's patient who also suffered from terminal heart failure, came to live at Julia's Home in February 2010, Roberto said. Membreno would on occasion hide in corners of the house or behind trees in the backyard, but never left the property until Sunday, Roberto said.

The facility has a chime that sounds when the door is open, but by law is not allowed to be a locked-down facility, the owner said. There are two or three caretakers at the home 24 hours a day, he said.

The family picked the facility for Membreno because of the chime system, said Sanchez.

"If it was working, she's not a marathoner, she's 86 years old. If she got out the door, why is it an hour before you call police?" asked Sanchez. "Something is not adding up."

Born in Nicaragua, Membreno moved to the United States 55 years ago and raised her two children as a single mother in the Mission District of San Francisco, working in a local hotel.

Contact David DeBolt at 925-943-8048 or Twitter.com/daviddebolt. Contact Erin Ivie at 925-847-2122 or Twitter.com/erin_ivie.