Alberto Martinez, a homeless laborer, pedaled around Wildwood with a wooden bat resting in a holder on his bicycle, authorities said.
On May 10, Martinez allegedly swung at Vincent J. DeSario, hitting the 19-year-old once in the head, said the Cape May County Prosecutor's Office.
DeSario, a member of the Middlesex County College golf team, had tripped over a curb before the attack. His nearby teammates laughed, and Martinez - who happened to be pedaling by - thought they were laughing at him, authorities said.
DeSario, 19, had been hospitalized since the attack. He died Monday of blunt-force trauma, authorities said. Martinez, who faced aggravated assault charges, has been charged with murder, authorities said.
He was being held in the Cape May County Jail on $350,000 bail on Tuesday.
DeSario, a 2008 graduate of J.P. Stevens High School in Edison, would have marched in Middlesex County College's graduation on Thursday with a liberal arts/business associate's degree with high honors, said Tom Peterson, a university spokesman.
During graduation rehearsal last week, the college president mentioned DeSario and asked students to think about him, the school said.
"It's just sad and unfortunate," said athletic director Robert Wisniewski.
DeSario and two teammates were in Wildwood that weekend to compete in a regional community college golf championship in Cape May, Wisniewski said.
The trio had qualified for the regionals, a precursor to the nationals. They had dinner with their coach that evening, Wisniewski said.
Later, the three walked toward the boardwalk and ran into Martinez shortly before 8 p.m., authorities said.
Martinez rode off on his bicycle after hitting DeSario, authorities said, and officers caught him a few blocks away.
Wildwood police referred questions on Tuesday to the Prosecutor's Office.
DeSario's family members could not be reached for comment.
"It's a very close-knit family," said Wisniewski, who spent time with family members in the hospital.
Wisniewski recalled that DeSario asked if he could hit plastic golf balls in the gym when it was not being used.
"That was his passion," Wisniewski said.
DeSario encouraged other players to attend the college and play golf for the school, Wisniewski said.