Almost a week after a Domino's Pizza driver was shot and killed while delivering a pizza, the owner of the Sioux Falls restaurant is pleading with the public for help solving the homicide.

Susan Graves spoke fondly in remembrance of Casey Bonhorst and asked for people with knowledge of the crime to come forward while speaking at Tuesday's police briefing.

Bonhorst, 30, was gunned down in eastern Sioux Falls on Feb. 29 while walking back to his car after the delivery.

"We need your help," Graves said. "We need to find the person or people who are involved in this heinous crime."

Earlier:Shooting victim's family grapples with loss of 'a good soul'

A $25,000 reward has been offered by the ATF and Domino's for information in connection to the shooting.

Police spokesman Sam Clemens said police still have no suspects, but they are operating under the assumption that the killing was the result of an attempted robbery. Clemens said people in the area of the shooting -- 2800 block of East Bragstad Drive -- need to check their surveillance footage for potential evidence.

Bonhorst , 30, grew up in Viborg and graduated from high school in 2008.

More:Eastern Sioux Falls residents rattled after homicide of Domino's delivery driver in neighborhood

Graves said Bonhorst was a kind man who would do anything for anybody.

"He would give you the shirt off his back," Graves said. "That's the kind of guy he was. He wasn't just an employee. He was a part of our family."

Graves also thanked the people who came to Bonhorst's side after he was shot. The Argus Leader interviewed two neighbors who said they were either with him and tried to render aid after the shooting or were the first to call police.

"When I read that in the paper, as hard as it was to read, it was comforting to know that he wasn't alone that night," Graves said.

Domino's has also been inundated with cards, phone calls and other items from the public after the shooting, Graves said.

"It has been incredibly heartwarming," she said.