FREMONT (WTOL) - A homework assignment uncovered an untold tragic story. Details of sexual assault to three siblings were revealed in an honest local high school essay.

Anthony Knight, 43, is headed to prison after pleading guilty to three counts of rape. The victims, his family.

Detectives say it’s because of their courage and vulnerability that Knight will spend 20 years in prison and register as a tier three sex offender.

Powerful words written on paper. That's what broke a case for the Sandusky County Sheriff's Office.

“The class was asked, I believe, to write an essay pertaining to obstacles that they had overcome in their life and she had disclosed that she had been sexually abused as a child,” said Detective Sergeant Kenneth Arp with the Sandusky County Sheriff’s Office.

After getting the assignment the school, Vanguard Tech Center, turned the case over to children services and the sheriff’s office.

Detectives learned Knight sexually assaulted three siblings for multiple years in several ways from as young as 7-years-old.

Detectives, school officials, the prosecutor’s office and more worked the case that happened years ago, but just came to their attention.

”The biggest thing was the help and support that I got from the school,” Detective Arp said. “They were a tremendous asset in the investigation."

School Superintendent, Greg Edinger declined an interview for the student’s protection, but did say student safety is the school’s top concern.

Detectives say it was the assistance of school personnel and quick action that helped them solve the case.

“I think that these types of things happen a lot more often then what the average person might think that it does,” Detective Arp said. “I think that if you talk to different investigators around the area they will tell you that they work a lot of sexual assault cases similar to this. This one happens to have a positive outcome and unfortunately a lot don’t, but I think it sends a great message.”

That message, Detective Arp said, is to show survivors of sexual assault that law enforcement will investigate cases thoroughly and should show perpetrators that they are serious.

Anthony Knight was indicted on 12 counts of rape, but pleaded guilty on Tuesday to three counts of rape. He will face two decades in prison. Detectives say this is a win for their community.