Eder Mike Marroquin, 33, of Castro Valley was fatally shot during an altercation at a house party held in a garage on Denning Court shortly before 8 a.m. on December 4, 2016. Witnesses say the dispute was with another party attendee, 25-year-old Ryan Gutierrez of Hayward, who reportedly pulled a black semi-automatic firearm from his waistband and shot Marroquin once in the abdomen. Bystanders attempted to de-escalate and render aid, but Marroquin died at the scene.

Gutierrez fled in a red Ford Mustang and was arrested about four hours later on Foothill Boulevard. He was charged with murder and two counts of being an ex-felon in possession of a firearm; court documents note he has prior felony convictions including insurance fraud, assault with force likely to produce great bodily injury, and first-degree residential burglary. Witnesses told investigators Gutierrez had exhibited the firearm earlier that evening and tensions between him and Marroquin had been evident.

Marroquin’s death was one of three homicides in Castro Valley within a month, a spike that drew attention to gun violence in the community. Did anyone at the party or nearby that morning see something that could help clarify what sparked the argument?