Security at Ontario Mills Mall first took notice of Chang Qui's black BMW in the parking lot Monday.
"They thought it was peculiar because the windows were fogged up on it," said Officer Dereck Anthony of the Ontario Police Department. "They looked inside and saw there was a Golden Retriever laying on the back seat of the vehicle."
Police said the 1-year-old dog was in distress suffering from a severe heat stroke.
Officers arrived just as Qui was coming out of the mall.
"She told our officer that she parked the car about 4 p.m. and we got there near 7 p.m.," Anthony said. "The dog had been in the car with the windows rolled up for three hours."
The puppy was taken to an emergency animal clinic where veterinarians were forced to put it down.
"It's against the law to leave your pet inside the vehicle, doesn't matter if you're just popping in to a 7-Eleven to grab yourself a Slurpee. You can't do it," said John Welsh of Riverside County Animal Services.