Might not have been a person - could have been an animal or slugs/snails - my mates lost a few this year to either rats or squirrels getting into the green house. They bit the top off an easy sativa but it was laid on the bench and he manage to root it in a glass of water and now it's in a pot but a 5th of the size of her sister. In the end he bought a livetrap squirrel trap and caught 1 rat that was rehomed about 10 miles away.
You might like to try something like Halo or Harpin protien to try and encourage some aditional growth to make up for what's been lost.