The late-night attack happened May 1 in the 2800 block of Southeast 14th Street.

Charles Brown, 65, of Des Moines, died as a result of the injuries he sustained during the attack. Police said the case is now being investigated as a homicide.

Brown was riding along the northbound lanes when two men jumped him, punched him in the face and knocked him off his bicycle, according to police.

“We’ve got a great witness who did the right thing and stayed and checked on Mr. Brown’s condition and talked to police and provided the investigators with some information,” said Des Moines police Sgt. Paul Parizek. “But it’s still holding as a ‘Who done it?’ so we need as much help as possible from the community.”

The suspects are described as white males in their 20s. The men left the scene in a silver 1996-2003 era Pontiac Grand Prix four-door sedan.

Katy Speck said she saw the two suspects moments before the attack.

“A guy got out of the silver Grand Prix, hit him in the face, then got back in the car and drove off,” Speck said.

Police found Brown seriously injured and bleeding in the roadway. He was not coherent enough to answer questions.

The case remains under investigation.

Anyone with any information is asked to call the Des Moines Police Department at 515-283-4811 or Crime Stoppers of Central Iowa at 515-223-1400 or submit a tip through their website at www.crimestoppersofcentraliowa.com.