Anthony Avalos was found unresponsive last Wednesday after allegedly falling in his home. He died the following day. The death has been deemed suspicious by the Los Angeles County Sheriff's Department.
Authorities say they arrested Kareem Leiva, 32, who is the boyfriend of Anthony's mother, in connection with his death.
Leiva was arrested after an interrogation by detectives on Wednesday morning that led them to believe he was responsible for Anthony's death.
Los Angeles County Sheriff Jim McDonnell said Leiva had a previous injury that required medical attention - a laceration to his chest that is believed to be self-inflicted. After he was arrested for murder, he was transported to a local hospital for treatment.
McDonnell said after he is medically cleared, Leiva will be booked in the Lancaster jail and held on $2 million bail.
The boy's mother, Heather Barron, has not been arrested in connection with his death.
Eight children that had been in the home have been removed and placed in the custody of the Los Angeles County Department of Children and Family Services.
As authorities investigate the boy's suspicious death, authorities say his sexuality may have been a motivating factor in his death.
Brandon Nichols, deputy director of the Los Angeles County Department of Children and Family Services, revealed in an interview Monday that Anthony "said he liked boys," but Nichols declined to provide more details, including whom the boy told and when, the Los Angeles Times reported. Nichols said the criminal investigation of the deadly abuse is ongoing.
Since 2013, DCFS reported receiving at least a dozen referrals for possible physical, emotional and sexual abuse of the boy. No such reports had been made in the last two years. Authorities are reviewing the agency's response to those reports.
Bobby Cagle, director at the Department of Child and Family Services told Eyewitness News that the department is investigating whether homophobia played a role in the boy's death.
"One of the things that we have heard is that there may have been a motivation on the part of the man in the household regarding to the sexuality of the child, and so we're looking into that in a very deep way. Of course, that was an alleged factor in the Gabriel Fernandez case, so that concerns us and so we're looking at that angle as well as many others," Cagle said.
Gabriel, 8, was murdered in 2013 after he was tortured for a long time and ultimately beaten to death. His mother and her boyfriend were convicted in the boy's killing. They were sentenced earlier this month. In Gabriel's case, there were also previous reports of abuse to DCFS.
Department officials said it investigated 13 allegations of child abuse at Anthony's home between February 2013 and April 2016.
"We know that the child had severe head injuries, including a brain bleed, contusions and bruises all over the body, really horrific kinds of injuries to the child," Cagle said.
Cagle said the allegations included physical and sexual abuse.
City News Service contributed to this report.