BAINBRIDGE ISLAND - Four Bainbridge Island teens are accused of exposing themselves over and over again to a 15-year-old boy with autism. And it allegedly happened while they were all at Bainbridge High School.

Police and prosecutors say it happened over 50 times throughout the school year -- a systematic pattern of harassing a kid with the mental capacity of a 10-year-old.

Police think it may have started innocently when the victim happened to see one of the teens urinating in public and "freaked out". His reaction led to a pattern of harassment.

"It went from something that somebody thought was funny," says Bainbridge Island Deputy Police Chief Mark Duncan, "to an intentional infliction of emotional distress."

Kitsap County prosecutors say the 16-year-old suspect also rubbed his genitals up against the victim. That teen has been charged with assault with sexual motivation. But the three other teens allegedly joined in the harassment.

"It's one thing to have a single individual," adds Deputy Chief Duncan, "but when you have four students who actually found entertainment value in this kind of conduct, I think that's somewhat troubling."

Court documents show the victim's mother told school officials about the harassment in September and again in November. When nothing happened, she finally went to police in January. High school principal Brent Peterson says they didn't know about it until November.

But instead of calling police, the school investigated.

"Once we had names and information to share," says Peterson, "we shared that information with police."

That wasn't until mid-January -- two and a half months after the school first heard the allegations.

Peterson says they did encourage the parents to report to police immediately.

The case raises questions about how this harassment could happen for months on school grounds, virtually under teacher's noses.

"Certainly that causes us concern," says Peterson, "and it's an issue that we look at very carefully."

Since the police learned of the case, a second victim has also come forward -- another male student with autism. Several witnesses have also come forward saying they saw the harassment take place.

Three of the four suspects have been released from juvenile detention. All four are no longer allowed to attend school there.