They have home surveillance footage of the vandalism, it seems.
https://archive.ph/lI4ym

Alladin says he feels like the school district's letter to family's on Friday, which took place after yet another unidentified incident on Thursday night, is too little too late.
"My biggest thing has just been frustration with the school itself," he said. "After going public on social media (Thursday), I was contacted by numerous people who had similar experiences due to race, sexuality, one person who reached out has a son who is autistic and was bullied, and all of them said the same thing, we never got anything accomplished from the school, unless we threatened to go to the media."

This bit has me a little more skeptical.

The archive of the article was cut off, likely due to the site loading more articles at the bottom. Here's the rest:

To make matters worse, he says his son already left the school last year due to mental health concerns.
Kent Erdahl: "How's your son doing?"
Chad Alladin: "He's okay. We've been trying to keep him out of this as much as possible. We didn't allow him to see what was on his car. He's been trying to go about life as normal and I asked him repeatedly if he was okay going down this road because my biggest concern is his mental health.
I'm hoping law enforcement will pursue charges against those they can identify. As far as the school goes, I have no faith they'll do the right thing."
The Le Sueur County Sheriff's Office confirmed Friday that the department is investigating the incident and working to identify the individuals involved.