OKLAHOMA CITY - A 24-year-old Oklahoma City man with no criminal history is facing 20 years in prison for what his family calls a terrible accident.

Zacary Anderson was led away in cuffs today to begin serving the sentence for child neglect. His family says justice was not served.

“He’s not a criminal. He's just a young father who made a mistake," said Anderson’s sister, Brittany.

Back in 2014, when Anderson was just 20, he was giving his infant son, David, a bath. David was in a baby seat. Anderson says he left the David alone in the tub for a few minutes to check on his other son when David apparently fell forward into the water. He was under water for several minutes causing severe brain damage. 

"It wasn't til later at the hospital that he found out what had happened to his baby. And he blames himself. Everyday,” Brittany Anderson said.

Defense attorney David Slane said, "I think this is a tragic accident. This is a father who never intended for his child to be injured in any way."

Oklahoma County District Attorney David Prater replied,  "Some call it a tragic mistake. You know there are things that you can do to avoid those types of, if you want to call it a mistake. You can avoid those things. That's by being responsible."

"I mean, his attitude sealed his fate as much as anything. He may as well have cut his throat in front of that judge when he kept talking to her and some of the things he said at his sentencing today. I mean, he cut his own throat."

Anderson's family doesn't believe he's guilty of a crime, and that this was just a horrible accident.

"This was an honest mistake that any parent could make." Brittany Anderson said.

State law requires Anderson serve at least 17 years of his 20-year sentence.  Anderson's attorney plans to appeal.