Redlands police said the sketch reflects new eyewitness information. The suspect is described as being 5 feet 5 inches tall, weighing about 150 pounds.
Police said he fled in a dark Honda or a similar vehicle.
On Jan. 5, Quinn McCaleb, 17, and Andrew Jackson, 16, were shot and killed near a playground at Oxford Drive and Colton Avenue in north Redlands.
The families of the victims are pleading for the public's help.
"We miss our children every day, and the surviving victims are traumatized tremendously. I would just like to ask that anyone who is God fearing to please come forward," said McCaleb's mother, Shanita Williams.
It's unclear why the suspect targeted the teens.
A $10,000 reward was offered by an anonymous donor a week after the shootings.
Police said they've run out of leads.
"No information or piece of information is too small," Redlands Police Department Chief Mark Garcia said. "We need to have any and every piece of information that might be vital to helping us solve this crime."
Anyone with information related to the case is asked to call Redlands police at (909) 798-7627.