A 'hero' pet dog has helped a couple in the US discover that the family babysitter was secretly abusing their seven-month-old son.
The 22-year-old babysitter, Alexis Khan, pleaded guilty to assault and battery in Charleston County Circuit Court, last week.
Benjamin and Hope Jordan hired Khan to babysit their son, Finn, last year after they moved to Charleston.
Khan had come up clean in a background check, according to the couple, but they got suspicious when their dog, Killian, became aggressive towards her.
"About five months into her being our baby sitter, we started to notice that our dog was very protective of our son when she would come in the door," Benjamin told WCSC-TV.
"He was very aggressive towards her and a few times we actually had to physically restrain our dog from going towards her," Benjamin added.
The couple placed a cell phone under the couch to record whatever happened while they were at work.
When the parents got home, they listened to the tape and were horrified to hear Khan cursing and slapping their child.
"It started with cussing. Then you hear slap noises and his crying changes from a distress cry to a pain cry. I just wanted to reach through the audio tape, go back in time and just grab him up," Benjamin said.
Charleston City Police arrested Khan a few weeks later, and she confessed to the crime.
Khan was ordered to serve one to three years in prison and will be placed on a child abuse registry.