A real-life Lassie story unfolded in South Carolina earlier this year when a dog alerted its owners to the possibility that their infant son was being physically abused by his babysitter.

After moving to Charleston last year, Benjamin and Hope Jordan hired Alexis Khan, 22, to babysit their then-two-month-old son Finn.

"About five months into her being our baby sitter, we started to notice that our dog was very defensive of our son when she would come in the door," Benjamin Jordan told Live 5 News. "He was very aggressive towards her and a few times we actually had to physically restrain our dog from going towards her."

Armed with suspicion, the couple decided to leave a smartphone underneath the couch and set it to record the scene while they were away.

Sure enough, the audio confirmed their worst fears.

"It started with cussing," Jordan recalled. "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."

Khan was subsequently arrested and, thanks to the audio captured by the Jordans, she was left with no choice but to confess to the crime.

She was sentenced to three years in prison, but will be eligible for parole after one.

Additionally, Khan, who had no prior record, will be required to register with the child abuse registry, banning her from ever working with children again.

"To know that five months I had handed my child to a monster, not knowing what was going on in my house for that day," Jordan said. "Had our dog not alerted us to the trouble, had my wife's instincts not said we need to make something happen, it could have been Finn that was killed by the babysitter. You never know."

[screengrabs via WCSC]