A man suspected of killing four people at his ex-girlfriend’s home in suburban Denver allegedly threatened to kill her a week before, according to court records.Police were searching Monday for Joseph Mario Castorena, 21, in connection with the shooting that left three men and a woman dead in Aurora. Neither the ex-girlfriend – identified in a protection order requested on Oct. 24 as Jessica Serrano – nor two young children at the home were injured in the shooting early Sunday, Aurora police said.Castorena and Serrano have two children together but they do not currently have custody of them, according to protection order applications made by Serrano and her father, Jose Serrrano, last week. At a news conference Sunday after the shooting, interim police chief Dan Oates said those children were out-of-state with family and safe. He also revealed that Castorena had been ordered earlier in the week to stay away from a ‘domestic partner’ and her home. Police department spokesperson Sgt. Faith Goodrich confirmed Monday that he was referring to Serrano. ‘This was an accumulation of events that led to this,” Oates said.Authorities have not released the names of those killed. However, a relative, Ubaldo Condina, told KUSA-TV that those killed were Jose Serrano, Jessica Serrano’s twin sister and her husband, whom he identified as the parents of the children found at the home, as well as a man who rented an RV on the property.In her Oct. 24 application for a protection order against Castorena, which was granted the same day, Jessica Serrano said Castorena pulled out a gun and threatened to kill her the day before. She also claimed he held her in his car and would not let her go home.In his application for a protection order, Jose Serrano said his daughter never came home from work on Oct. 22, and on Oct. 23 she showed up covered in glass with cuts all over her arms. He claimed Castorena broke the driver’s side window of Jessica Serrano’s car as she was sitting next to it. He also said Castorena had previously threatened to kill him if he did not give him his children, the document said.A woman identified as Jessica Serrano’s sister also requested a restraining order against Castorena but there is no record of it being granted. It did not mention a specific threat made against her but said that she and her family had been dealing with problems between her sister and Castorena for three years. In the hours after the shooting, police searched the nearby home where Castorena lives with his family but did not find him and his car was found unoccupied, Oates said.