(KRON) -- Court documents reveal haunting details about what happened inside a Richmond family's house before one of the family members allegedly killed four victims by igniting the house on fire. Sergio Rivera-Vega, 32, is charged with murdering four family members in the August 18 arson blaze: h is father, his sister, and the sister's children. The youngest victim in the tragedy was a 2-year-old girl, Arlette Rivera-Vega. Arlette's mother, 33-year-old Maria Rivera-Vega, was among the house fire victims. When she filed for a restraining order against Sergio Rivera-Vega in 2022, Maria Rivera-Vega wrote about violent threats that made her fear for her children's safety. A photo of one of the Richmond house fire victims is seen at a memorial. (KRON4) During one incident in February 2022, Sergio Rivera-Vega threatened his sister with a metal bar, according to court documents filed in Contra Costa County Superior Court. "I was terrified because he said he was going to kill me (with) the metal bar and my 1 year old son was in my arms," the sister wrote. "He told my mom to grab my baby cause he was going to kill me." Maria Rivera-Vega wrote that her brother would become "aggressive" when he used drugs. Her request for a restraining order states, "He needs to get away from me because I fear he (is) going to harm my baby." Sergio Rivera-Vega is seen in an August 2026 mugshot released by Richmond Police Department. She also wrote about an incident that happened in Nov. 2, 2021. Maria Rivera-Vega wrote that her brother "said he was going to burn the house and broke doors of the rooms. When he is (drugged) up he tries to fight everyone in the house. He has said that one of these days he's going to burn the house while we sleep so that we all can die," she wrote. Drugs made Sergio Rivera-Vega believe that his family were not his real family, but rather, renters who were living in the house for free, court documents show. He allegedly threatened to "kill all of us because we are not his family," the sister wrote. After Sergio Rivera-Vega was eventually jailed, his sister wrote that he had been diagnosed with schizophrenia as a mental illness. On August 18, firefighters found the family’s house in flames with Maria Rivera-Vega, her two children, and her father still inside. Firefighters pulled the victims out, however, all four later died from their injuries. Police officers found the suspected arsonist nearby and arrested him. Police officials said Sergio Rivera-Vega was still living in his family's house leading up to the tragedy. The Richmond Police Department said it "extends its deepest condolences to the family and loved ones during this incredibly difficult time." Richmond house fire victim Jose Rivera In court documents, the four victims were identified as: Maria Rivera-Vega Arlette Andrew Alexander Rivera-Vega, the suspect's 5-year-old nephew Jose Rivera, the suspect's 47-year-old father Sergio Rivera-Vega has not entered a plea. He is in custody and scheduled to return to court on Sept. 8. ...read more read less