PORTLAND – A former water delivery man who forced his way into a home and sexually assaulted a 10-year-old boy said he could understand why people think he’s a “monster,” before he was sentenced to eight years in prison.

Derrick Coffin, who admitted guilt as part of a plea agreement, will serve eight years of a 15-year sentence followed by 10 years of probation.

He will have to register as a violent sexual predator for the rest of his life.

The victim’s family was happy that the plea agreement spared the boy from having to testify, but they were angry over the sentence.

The boy’s father described how his son now is afraid to shoot baskets outside his house or play with the family dog in the yard, and that he has nightmares. He’s in counseling and his mother worries about the crime’s long-term effects.

The assault happened Sept. 2 when Coffin stopped at the boy’s Raymond home to ask directions. He parked his water delivery truck in a nearby neighborhood and returned wearing nothing but a dark towel with eyeholes on his head.

Coffin forced open the door and began assaulting the boy but fled when he realized the boy was not alone in the house.

“I completely understand why people would call me a monster,” Coffin said Friday in Cumberland County Superior Court. “I do want to get it straightened out, and I do want to be a contributing member of society when I get out.”