Seeing that the person had intentions to kill the animal, it's currently being neglected, and you've got suspicions of him beating the poor thing [I'm not sure if this was the same person, but it'd still count as people on the property did this], it certainly would count as animal abuse. I'd notify someone of authority, whether it be a police officer, a humane society, anything that could help. If you're contacting a humane society/rescue group, they may be able to remove the animal from the property (or persuade the 'owner' into surrendering the animal). Eventually, if seen fit, you'd possibly be able to adopt the dog if allowed.