Police say they are investigating after a man who was assaulted while walking on the Manhattan Bridge earlier this month died.

Jonathan Mann, 61, was attacked just before 3 p.m. on Aug. 5 and sustained a head injury. He was transported to Bellevue Hospital after the incident and was later released.

"He loved the city with all of his heart, and he didn't deserve to die the way he did," his friend Scott Russo said.

Peter Klarnet, who knew Mann for nearly three decades, spoke to Mann after the attack. Klarnet shared with NY1 what Mann told him about the incident.

"All he told me was he was walking on the Manhattan Bridge towards Brooklyn. A man approached him with a very broad smile on his face and said something to the effect of 'It's now your turn to die,' or something along those lines. And that's the last he remembered. He said he got hit in the head, probably with a brick or some other large object," Klarnet said.

After being released from the hospital, Mann went to Staten Island to be with friends and recover.

"Last Tuesday, they were just walking on the lawn out front," Russo, who heard the account from a mutual friend, said. "He said, 'I'm having trouble breathing,' and he collapsed and died."

Mann was a writer, publisher and filmmaker. His friends say he greatly impacted their lives.

"What I really took, take away from knowing him is just his unwavering generosity. Incredibly generous, thoughtful and supportive person who did not deserve this," Klarnet said.

The city Office of Chief Medical Examiner is working to determine Mann's official cause of death, and police are continuing to investigate the assault.

"I did walk over the bridges with him several times and we never had any trouble, and they were beautiful walks," Russo said. "I hope everybody should be able to do that without fear of being killed."