He walked down one of the aisles. A woman was looking at products on the store shelves when the suspect walked behind her and grabbed her thigh and buttocks.
"She wasn't sure if it was a passing accidental bump or whether it was more purposeful," said Fullerton Police Sgt. Andrew Goodrich.
Seconds later, the suspect again groped the woman.
"He turned around, came back and approached her and grinded his pelvis region against her buttocks kind of in a thrusting maneuver," said Goodrich.
Police say the woman, in her early 50s, confronted him. They exchanged a few words. He left and she told a manager.
Police are concerned the suspect has done this before and that his actions could escalate.
"He has a comfortable level that kind of frightens us, that he would be so brazen in doing it," said Goodrich. "We also think that he may have had a cell phone in his hand, may have been taking photos himself, of the victim, or what he was doing," said Gingrich.
The suspect is described as 18 to 21 years old, 5 feet 9 inches tall, weighing about 160 pounds. He spoke with a British accent.
"It kind of creeps me out, especially because this is 24 hours so a lot of time I have small children, I'm coming here," said Fullerton resident Veronica Ramirez. "It's kind of scary to think there's someone in this neighborhood."
CVS officials issued a statement: "The safety of our employees and customers is our top priority and our Fullerton store's on-duty supervisor immediately responded when the incident was brought to his attention."
Police say the suspect drove off in a newer model Volkswagen Beetle. If you recognize the suspect, you're asked to call the Fullerton Police Dept. at (714) 738-5327.