The sketch was put together with the help of the third victim, a woman who says she woke up Tuesday morning with a man covering her mouth.
The new sketch is similar to those from two previous assaults at Park Regency Apartments in Walnut Creek.
In one instance, a woman says she was raped. The other two women were able to fight their attacker off.
The sheriff's office is also is asking anyone with information about any of the cases to call detectives at (925) 313-2625.