WATCH: Jake Patterson's family breaks silence

WATCH: Jake Patterson's family breaks silence

Transcript for Jake Patterson’s family breaks silence

There is also news reporting at this hour about that horrifying kidnapping and escape of 13-year-old Jayme Closs. New and chilling details of that plot. Prosecutors say Jake Patterson said why he chose to use a shotgun, how he burned her clothes to destroy evidence and how he boxed her in under the bed. His family tonight speaking out for the first time. Were there any warning signs? What they’re now saying. Here’s ABC’s Alex Perez. Mr. Patterson — Reporter: Tonight, the family of the man accused of kidnapping Jayme Closs and murdering her parents breaking their silence. His grandfather telling ABC news “Something went terribly wrong. Nobody had any clues. We are absolutely heartbroken. It’s wrenching to deal with,” adding that his grandson “Was shy and quiet. He backed off from crowds, but a nice boy, polite. Computer games were more of a priority than social interaction.” Patterson’s childhood friend stunned, too. Everyone liked him. He was a good student. He was pretty happy for the most part. Reporter: But prosecutors painting a picture of a cold-blooded killer who, according to court documents, chose a 12-gauge shotgun because he thought it would inflict the most damage. Later burning Jayme’s clothing to get rid of evidence. Often forcing the 13-year-old under his bed, boxing her in with laundry totes and barbells. Would you like to say anything, sir? Reporter: Tonight, Patterson’s family struggling to understand what went wrong. His father and brother silent as they left the courthouse. Did you know this was going on? Let’s get back to Alex Perez, live tonight again from Wisconsin. Alex, Patterson’s family is also describing his mother’s reaction when she heard the news. Reporter: David, family members say Patterson’s mother initially was hoping authorities confused her son with someone else. They say he had no mental health issues growing up. David? Alex Perez again tonight. Thank you, Alex.

This transcript has been automatically generated and may not be 100% accurate.

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