Refused a visit with his child, Brian Guzman broke a window at the residence of his ex-girlfriend then fled.
Thirty minutes later he was lying on the pavement with a broken skull.
Guzman, 21, died four days later. His ex's boyfriend, Fidel Gandara, 23, is charged with first-degree murder on allegations he beat Guzman to death with a baseball bat.
Gandara has pleaded not guilty and is being held on $1 million bail.
The events leading up to Guzman's death began around 6:30 p.m. Dec. 28 when he showed up at his ex-girlfriend's residence, according to recently released court documents.
The ex, whose name is redacted from the documents, told police Guzman looked "unhealthy" and she refused to let him see their child. She said Guzman used marijuana and "spice," or synthetic marijuana. She believed he was also using heroin.
Fearing Guzman would try taking their child, she closed the door on him, according to the documents. She said he struck a window, breaking it, then ran away.
The ex-girlfriend then made a couple calls. One was to police, another to Gandara, according to the documents. She told Gandara she was scared, and he offered to come over, she told police.
As police interviewed her, a call came in regarding a nearby assault. Officers arrived to find a man, later identified as Guzman, lying on the pavement with apparent blunt force trauma to his head.
A witness who saw the attack from inside his car told investigators the assailant, armed with a small wooden bat, hit Guzman at least twice as Guzman turned his back on him.
Guzman sat down upon being struck, his hands over his head, the witness told police. The assailant then struck Guzman at least four more times on or near his head. He left Guzman sprawled on the ground, blood pooling underneath his head.
The description of the assailant — both his physical characteristics and the clothes he wore — closely matched a description of Gandara and the clothes he was seen wearing that day, according to the documents.
Police arrested Gandara at his home. He refused to provide a statement, the documents say.
The ex-girlfriend repeatedly lied or withheld information from police, including at first denying calling Gandara, investigators said in the documents. Upon admitting calling him, she said she never directed him to harm Guzman.
She said Guzman had been involved with a "graffiti group" when he was younger, and he and Gandara knew of each other through a mutual acquaintance who is a gang member, the documents say.
Gandara is next due in court March 1.