A new surveillance video has been released in connection to the killing of Miami activist Dwight Wells, and police are hoping it could lead to a break in the case to help find his killer.

Police say the video shows the gunman who took the life of Wells running away from the scene after the killing.

Wells, 40, was shot and killed on Oct. 10 as he was playing dominoes while sitting outside his Liberty City restaurant.

Wells' mother, Mary Brown, is on a mission to find her son's killer.

"I asked God myself, 'Why? What for? Who,'" Brown said. "I don't know. I just don't know."

Wells's sister, Trawonna Brown, was also at Miami Police Headquarters on Thursday asking for anyone who may have information on the killing to come forward.

"I would just like to ask the people, if you know something, say something," she said.

And for the first time, we've heard from lead detective Roberto Gonzalez.

"The suspect was wearing a hooded sweater and a face covering," he said. "He appears to be thin to medium build. At this moment we don't have a motive."

Surveillance video showed people running away from Wells' restaurant after the shooting and showed a troubling image of Wells falling to the ground.

CBS News Miami's Peter D'Oench asked Mary Brown what it would mean to her for the killer to finally be captured.

"Oh, my goodness. It would mean $1 million once again to solve this case," she said. "My son was lovable, and I really want to know who shot my son. It would be a great relief to me. People don't know how I hurt. I want to know who is the murderer."

Gonzalez said it's not known if the killer had an accomplice or was running to a nearby car.

He said that, so far, they've only received a few tips.

If you have any information, you can call Miami Police or Miami-Dade Crime Stoppers at 305-471-TIPS.