Abusive babysitter revealed by dog's behavior

Story here. Excerpt:

'A South Carolina couple is thanking their dog for saving their 7-month-old from an abusive babysitter.

Benjamin and Hope Jordan, of Charleston, hired 22-year-old Alexis Khan to care for their son, Finn, last year.
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Suspecting that their pet might be on to something, the Jordans placed an iPhone under the couch to record what happened when Khan and their son were alone.

The recording revealed the babysitter swearing and slapping the infant as the child's cries changed "from a distress cry to a pain cry."

Khan pleaded guilty to assault and battery Monday and was sentenced to one to three years in prison. She will also never be allowed to work with children again.'