By Kristen Johanson

PHILADELPHIA (CBS) — It’s been more than two years since a Philadelphia Parking Authority employee was gunned down near his home in West Philly as he was walking his dogs. Detectives are still searching for answers and need the public’s help to find the killer.

Detectives say it happened on Dec. 16, 2015 around 8 p.m., when 34-year-old Mark Marshall was walking along Kingsessing Avenue near 47th Street in Squirrel Hill.

According to police, a man in his mid-20s, wearing an orange wool hat, jumped out of the passenger side of an older minivan and began arguing with Marshall, before shooting him several times.

“He would have been one of the last people that I thought would have been shot on the streets,” said Frank Halbherr.

Halbherr is the president of ASFCME, the union that represents PPA workers.

“We were all devastated, it was hard to get your brain around it, because of the kind of guy he was,” he said.

At the time Marshall was gunned down, he was also in the process of becoming a Philadelphia police officer.

“He was a man of high character who wanted to better himself,” Halbherr added.

Police say there is a $32,000 reward for information that leads to an arrest, and callers can remain anonymous.