(CNN) -- They had blood relatives in Houston who wanted to adopt them.
A guardian ad litem volunteer had concerns about the couple who had adopted them.
Child investigators were called to their home on more than one occasion.
Yet on Monday, the 10-year-old boy was found, burned and trembling, soaked with a caustic substance, and his twin sister dead in a body bag, in the back of their adoptive father's red Toyota pickup truck along a south Florida interstate.
Jorge Barahona, a 53-year-old father of four children adopted from the state's foster care system, told West Palm Beach police he was distraught over the death of his daughter and had intended to commit suicide by dousing himself with gasoline and setting himself afire -- but didn't go through with it. He was lying unconscious beside the truck when he was found by a roadside assistance ranger, leading to the gruesome discoveries inside the vehicle.
The boy was hospitalized with severe burns to his abdomen, upper thighs and buttocks, according to a probable-cause affidavit filed by detectives. While examining the boy, doctors noted he had sustained previous injuries, including a broken collarbone, a broken arm, scarring to his buttocks and lower abdomen, and ligature marks on both wrists, police said.
Barahona and his wife, Carmen, had been at the center of multiple complaints to Florida's Department of Children and Families, an official with the agency said Thursday. But investigations into those complaints never found cause to remove the children from the home. It wasn't until the last few days of the twins' life, and in testimony afterward, that allegations of profound abuse and neglect have emerged, including court testimony of a call to an abuse hotline reporting the twins were locked in bathrooms for long periods of time and bound with tape.
Jorge Barahona was charged Thursday night with attempted murder in connection with the injuries to his son, and police were executing a search warrant at the Barahona's Miami home, said West Palm Beach spokesman Chase Scott.
The Barahonas' story appears to magnify everything that could go wrong with a child protective system.
In 2004, the siblings were placed with a foster family, according to Sonia Ferrer, circuit director of the guardian ad litem program. That family was Jorge and Carmen Barahona.
As often is the case when children are in the Florida foster system, a volunteer from the guardian ad litem program was assigned to look out for the children's best interests.
"The guardian was with the children for four years," Ferrer said. "He had concerns about the placement."
When asked about those concerns, Jacqui Colyer, regional director for the Department of Children and Families, said, "In every case there's going to be one who may say, 'I don't think this is a good idea.'"
Colyer on Thursday said all the information showed that the Barahonas were decent people. She said the background check and the home study of the family was "absolutely stellar."
Ferrer said the guardian ad litem's concerns were brought to the court's attention and investigated before the children were officially adopted by the Barahonas in 2009.
"We did everything we could at the time," Ferrer said. "A full evidentiary hearing."
The judge on the case sided with the experts who found no problem with the children living with the Barahonas. Ferrer recently spoke to that guardian ad litem, who she says is devastated over what happened to the children.
He is not the only one.
The twins' biological aunt and her husband wanted to adopt them, according to their attorney Steven Grossbard.
"Unfortunately, the expert opinion suggested that there was a significant bond, and the courts are inclined to go with experts' opinion," Grossbard said. The bond he referred to was the five years the twins lived with the Barahonas as their foster children before their adoption in 2009.
Over the years, problems in the Barahona home were brought to officials' attention.
"Several times we've been out to the home," Florida Department of Children and Families spokesman Mark Riordan said.
One of those complaints came in June 2010, charging that the children looked "unkept" and unfed, Colyer said. An investigation into those claims was closed without any state action.
That same month, the little girl's endocrinologist, whom she has been seeing since birth, voiced concerns about her weight, according to testimony Wednesday by Dr. Walter Lambert, the state child protection physician who interviewed the girl's doctor. Lambert's testimony came during a placement hearing in Miami for the three surviving adopted children.
Carmen Barahona told the doctor the girl's weight was due to a diet, Lambert testified. He also said that during the appointment, the little girl's mother told the endocrinologist her office was too far away and she was going to change doctors.
The most recent -- and urgent -- cause for concern was a call the child abuse hotline received last Thursday, four days before the twins were found in the truck, according to Colyer.
Lambert testified Wednesday that the information in the hotline call came from the 7-year-old daughter of Carmen Barahona's biological daughter.
"When (the 7-year-old) would go to this home, where these children were being locked in the bathroom -- they were being tied, but they were being untied to eat," Lambert said.
The granddaughter was told by her mother and grandmother that she was to keep "family secrets" quiet, Lambert said.
This information was corroborated by interviews with the granddaughter and the two other adopted children, according to testimony. The 11-year-old brother in the home told investigators "that his siblings would be kept in the bathroom; that they would have their hands and ankles bound; that in particular, his sister did; that she would sometimes ... have to sit in the bathtub all day."
All the abuses alleged in the hearing were directed toward the twins. No allegations were made of the other two children being mistreated.
The hotline call was on Thursday, Colyer said. The DCF investigator, Andrea Fleary, said she went to the house on Friday night and Carmen Barahona told her she was separated from her husband, and that the twins were not home but with him. Fleary said she did not speak to the two other children in the house.
The department tried to reach Jorge Barahona on his cell phone on Saturday, Colyer said, but couldn't reach him. Another investigator went to the home on Sunday, and when he still wasn't there, "red flags" went up.
Jorge Barahona has been charged with aggravated child abuse, the West Palm Beach Police Department said, and likely will face other charges. Carmen Barahona has not yet been charged.
Carmen Barahona tried to hide her face at Wednesday's hearing, where the allegations of abuse were denied by her attorney.
Colyer said the adoptive mother's claim that the couple were separated "impeded the investigation."
"If we hadn't been lied to, we would have probably have moved to begin the process of trying to locate the father," Colyer said.
CNN's Alan Duke contributed to this report.