My take on this is that those who did this to a vulnerable teenager need to be publicly named and shamed. What on earth possesses some teenagers to take teen pranks and high jinks into the realm of pure cruelty? Picking on those who are vulnerable is something to be ashamed of. Didn't these teenagers have any inbuilt behavioural traits as to what is right and wrong? I suggest that they be made to perform community service by working with people with disabilities for a year. In this country this act would be classed as a disability hate crime. Here is a report, published by the University of Leicester, which is well worth a read and shows the amount of hate crime faced by disabled people (and other groups).
People with disabilities are not joke material.