EDWARDSVILLE, Ill. — A teenager was sentenced Friday to 30 years in prison for his role in the 2008 torture killing of a pregnant, developmentally impaired mother who police say died after weeks of systematic scaldings, beatings, burns from a glue gun and being used as target practice with a BB gun.

Benny Wilson, 19, twice declined to address the judge as the last of six defendants sentenced in Dorothy Dixon’s death, which police say Wilson admitted contributing to by routinely shooting her with BBs “playing around.” At least once when he ran out of BBs, an investigator testified Friday, Wilson used a knife to dig the ammunition out of Dixon’s flesh and fired them off at Dixon again.

Investigators have said Dixon was a 29-year-old mother with a childlike mind and another baby on the way when she was found dead in January 2008 at Riley’s Alton house, where she had been banished to the basement and given little more than a thin rug and a mattress to call her own on the chilly concrete floor.