Published: Aug 12, 2013 7:40 PM EDT

FORT MYERS, Fla.- A Fort Myers mother wants answers from the community, six years after her son was gunned down on Martin Luther King Jr. Boulevard.

Marilyn Savage says she wants the community to break its silence about what happened to her son the night he was killed.

In June 2007, someone shot and killed 27-year-old Robert Dunham. Today would have been his 34th birthday, and his mother says it's time someone speaks up.

She says, "it's our friends, or Robert's friends, so we thought, who are remaining silent about what happened to him, we want the silence to be broken. We want closure to the loss of our son, of our loved one. And until the silence is broken, we won't have peace."

She has a sign hanging outside her home with the words of Dr. Martin Luther King Jr., "in the end, we will remember not the words of our enemies but the silence of our friends."

After Dunham was killed, police arrested Brandon Battles, also known as Brandon Nash, and charged him with murder. But about a year later, the state attorney's office dropped the charges because witnesses changed their stories.

Savage says she was heartbroken. "I was devastated.My whole life was pretty much shattered. It's hard."

Police Chief Doug Baker understands her frustration.  "We're talking about homicide, a life sentence in most cases so when you have witnesses that are untruthful, when you have witnesses that recant, the state's not gonna file on that, and I'm frustrated with it. I understand they can't file on it."

Savage says she won't give up fighting for her son and pushing for answers. "I want to keep Robert's dream, his hope alive, that one day someone will come forward and break the silence. They say silence is golden but where is the gold? There's no gold."

On Saturday, Savage held a memorial ceremony for Robert at the location where he was killed. She hopes someone will hear her plea, and speak out about what they know. "When I'm silent, I'm just as guilty as the person who witnessed it. I need to speak up because I don't want my son's death to be in vain. I don't want it to be looked at as another black male doing something in the community"