The sketch, which was released on Tuesday, is based on eyewitness accounts.
The suspect is described as being in his early 20s, Hispanic, about 5' 5", weighing about 140 pounds, and has short black hair.
"The crime that we have right now is a burglary, a residential burglary. He'll reach in through a window, or take of the screen of a window, and reach into someone's apartment building and remove their underwear from their drawers in some cases," said Bill Russell, Ontario Police Department. "He hasn't made any attempts to harm anybody or to actually physically touch anybody at this point. We're hoping it does not escalate to that some day."
Ontario police have been patrolling the area and informing the residents of the situation.
Some residents say they now hide their underwear because of the thefts.
"Basically, I don't think about it that much because I'm pretty busy. But, other than that, we are taking more precautions to be safe and keep the house locked up," said resident Missy Bushell.
If you have any information on the suspect, you should call the Ontario Police Department at (909) 986-6711.