WATCH: Texas Man Charged With Murder of Teenage Boyfriend

A 20-year-old man has been accused of beating his 18-year-old boyfriend to death after an intoxicated argument in the couple's apartment in Austin Friday, according to local TV station KTBC.

Bryan Canchola and Stephen Sylvester's roommate told police that the couple came home drunk and started screaming at each other. According to a police affadavit, the roommate overheard Canchola yelling at Sylvester, "Why would you cheat on me?" The roommate, whose name was not disclosed, decided to intervene after he noticed that Sylvester had a cut on his head. He told police that he took the teenager to University Medical Center Brackenridge.

The affidavit reports that Sylvester left the hospital without being treated. When the roommate couldn't find Sylvester, he returned to the apartment, where the door to the couple's room was closed, he said.

Austin police received a 911 call from Canchola around 5 a.m., explaining that Sylvester was unconscious and bleeding from the back of his head. Sylvester was transferred to the hospital at Brackenridge, where he died.

An autopsy revealed that Sylvester "had bleeding of the brain and a traumatic neck bone fracture from what appeared to be strangulation," according to KTBC. His death was ruled a homicide.

Sylvester's dog, a Yorkshire terrier, was injured in what appeared to be a strangulation attempt. The roommate said he heard Canchola threaten to kill the dog.

Police suspect that Canchola believed Sylvester had been unfaithful. Canchola has now been charged with first-degree murder and is currently being held on bail set at $500,000, according to the Associated Press.

Watch KTBC's report below.

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