Prosecutors said Phoenix yelled racial and anti-gay slurs at the men and cracked Jose Sucuzhanay's skull while beating him with an aluminum baseball bat in a Brooklyn neighborhood.
Jurors deliberated for more than 30 hours over four days. They requested hours of testimony and re-watched a video of Phoenix admitting that he hit the victim with a bat. On Monday, they said they were deadlocked on one count but did not specify which one.
They were twice given orders by Judge Patricia DiMango that they had to reach a unanimous verdict.
At about 9 p.m. Tuesday, the jury sent a note to the judge saying one of the jurors was refusing to deliberate. DiMango asked them if it would be helpful to go home for the night and resume Wednesday. They shook their heads no.
"We have read back testimony over and over again," she said. "I can't see any other action then to declare a mistrial at this time."
Phoenix will be held until a new trial, set for June 15.
Prosecutors declined to further comment.
Phoenix's mother, Marietta Phoenix, said outside court that she was happy with the outcome because her son was wrongly characterized as someone who was capable of murder.
"My son is not an animal as everyone is making him out to be," she said. "I think justice was served at least a little bit."
Romel Sucuzhanay said outside court that he was unable to speak much on the mistrial because he will have to testify again.
"My family, we feel very worried. The evidence was there," Sucuzhanay said in Spanish. "I hope that we have success in the new trial."
Phoenix had pleaded not guilty to second-degree murder, manslaughter and attempted assault, all as hate crimes. His attorney, Philip Smallman, said in closing arguments that the case was about a fight that escalated, not a premeditated attack.
Phoenix's co-defendant, Hakim Scott, was convicted Thursday of manslaughter but acquitted of a more serious murder charge, and the jury found his actions were not a hate crime. He faces 25 years in prison on the top charge when he is sentenced June 9.
Two juries had been hearing the case in state Supreme Court in Brooklyn because the defendants had implicated each other.
The brothers were walking home from a bar after a party at a church in Brooklyn on Dec. 7, 2008. Romel Sucuzhanay had put his coat around his brother to keep him warm and was helping him walk because he was drunk, according to trial testimony.
Meanwhile, Scott, 26, Phoenix, 30, and a teenage relative of Phoenix's, also leaving a party, pulled up in an SUV. They began yelling anti-gay and anti-Hispanic slurs, according to Assistant District Attorney Josh Hanshaft. Jose Sucuzhanay became upset and tried to kick the wheel of the SUV, and Scott got out and smashed the beer bottle on his head, then chased Romel Sucuzhanay with it down the block, according to testimony. Phoenix grabbed a bat from the back of the SUV and attacked Jose Sucuzhanay.
A jury hearing Scott's case sided with his attorney, Craig Newman, who said the incident was not motivated by hate. Scott would have faced steeper prison time if he been convicted of hate crimes.
"For Hakim Scott, this was never about hate or prejudice, and that's exactly what the jury came back with," Newman said after the trial.