LOS ANGELES -- The grandfather of Gabriel Fernandez, a Palmdale boy who authorities say was tortured to death by his mother and her boyfriend, sobbed in court on Monday as he testified about his beloved grandson, who he said he practically raised as his own son with his late wife.Testimony continued in the trial against Isauro Aguirre, the boyfriend of Gabriel's mother, Pearl Fernandez.Prosecutors allege that Aguirre and Pearl abused and beat 8-year-old Gabriel to death. Gabriel's mother will be tried separately for his murder.At the time of his death, Gabriel suffered a cracked skull, broken ribs, burns and had been shot with a BB gun.Gabriel's grandfather, Robert Fernandez, said his daughter and Aguirre had taken Gabriel from him and his wife's home, although the grandparents had custody.He also raised Gabriel's siblings Ezequiel and Virginia, he said, but Gabriel was closer to them. Robert added that around 2009, Ezequiel and Virginia went to live with Pearl and Aguirre and Gabriel stayed with them."We had custody of him," Robert testified. "I didn't think Pearl wanted him."Robert said he loved Gabriel and wanted to keep him and Gabriel also wanted to stay with him and Sandra, he said.He testified that at one point, Pearl, Aguirre, Ezequiel and Virginia moved to Palmdale to Robert's house while Gabriel had stayed with him and Sandra. He said he tried to get Gabriel and Pearl to bond during this time.Robert said Gabriel slept with him and Sandra, but when the kids moved in, he allowed Gabriel to sleep in the room with Pearl, Aguirre, Ezequiel and Virginia. The grandfather said he once or twice found Gabriel in the living room sleeping by himself, which made him upset because Pearl told him she wanted to bond with Gabriel.Robert testified that one day, Aguirre told him there was going to be a barbecue at his parents' house and wanted to know if Gabriel could go with them. Sandra said not to let Gabriel go, Robert testified. He then told the jury he drove around Aguirre's parents' house and didn't see any barbecue. After that, he said he went back to his house and confronted Aguirre and Aguirre told him the barbecue was happening inside.Robert broke down on the stand when the prosecution played a 911 call made by his wife, Sandra Fernandez. Gabriel's grandmother had reported that her daughter and Aguirre, who she refers to as Tony, took Gabriel."So you told Tony, the defendant, that you had to take Gabriel to school?" the prosecutor asked the grandfather."Yes," he replied."He promised, he swore to God he would bring Gabriel back," the prosecutor added."Yes, he said he promised," Robert replied."Did he ever bring Gabriel back?" the prosecutor asked."No," Robert said.Robert said he and Sandra cared for Gabriel nearly every day of the first 7 1/2 years of his life. Robert stated on the stand that Gabriel was like his son.He added that Gabriel would be taken to the doctor while living with him and Sandra, was fed properly, taken to school and loved "always."Between October 2012 and May 2013, Robert said he saw Gabriel about two or three times after he was taken by the defendant and Pearl, but he wanted to see him more times."Do you remember the last time you saw Gabriel alive?" the prosecutor asked."It might have been one month or two months before he passed away," Robert replied.Overpowered with emotion, Robert shared one of the last conversations he had with his grandson."He said he wanted to come home. I told him that...the DCFS was investigating the case and I couldn't bring him home, but that they were, one of these days, going to bring him home. And I promised that to him," Robert said, as he struggled to hold back tears.Gabriel's grandfather is expected to testify again Tuesday, as well as the boy's aunt.Aguirre is facing murder charges with special circumstances and could face the death penalty.