Investigators say the suspect knocked 28-year-old Karmond Stafford unconscious and left her to die last week at the Foothill Villa Apartments on West Second Street.
She was pronounced dead at the hospital.
Police say the man actually assaulted her twice.
The first time, they were seen leaving the apartments together.
She was killed after they returned.
Anyone who recognizes the man should call San Bernardino police detectives at (909)384-5745 or (909)384-5613.