SAN FRANCISCO (KGO) -- A family has been grieving for almost two years over the murder of their son, which remains unsolved.
His birthday is Saturday and his killer is still out there.
San Francisco police say the man pictured riding on the handlebars of a bicycle could well be a killer. Just a short time earlier, they believe he shot 24-year-old Mitchell Warren, who died from his wounds.
The shooting happened on Ellis Street near Polk, an area with a heavy concentration of security cameras.
But while they have the suspect's image, they don't have his name.
"We think this is an extremely solvable crime, a horrific crime that took the life of a member of our community. And we think with the public's assistance, we can take the perpetrator off the street," SFPD Commander Greg McEachern said.
The murder happened nearly two years ago, in September of 2016.
Warren's father remembers having to break the news to the victim's older sister, just days before her wedding.
"The hardest thing I ever had to do in my life was to call my daughters and tell them their baby brother had been shot and killed," said the victim's father, Lary Warren.
"He had rented his tux, he was supposed to be there. And not having him there and still knowing that the individual who did this to him, and has shaken my family to its core is still out walking around free. This has to come to an end," said the victim's sister, Ashley King.
Police have images from several angles. One shot from behind shows the suspect, wearing a Giants cap and a dark-colored sweatshirt with the word "fringe" on the back.
The shooting happened early in the morning hours and police have not disclosed a motive, except to say that Mitchell Warren had argued with the gunman.
Still, they believe with the right tip, the suspected killer could be quickly brought to justice.
"We cannot do it without the public's assistance," said McEachern. "Please help bring justice to Mitchell Warren and for some closure to his still grieving family."
Police have posted the videos and photographs in this report along with others on the SFPD website.
To get a good look at the surveillance footage of the suspect, click here.