It is unclear how many times the child was raped, or when the sexual abuse began.
Prosecutor Dan Dry said: “She reported it to a relative that mom’s boyfriend had been abusing her for the last two weeks.
“Multiple counts of rape committed by the male, and at least one incident of rape where the mom of the child actually physically held the child down to assist this male.”
Carpenter was sentenced to life in prison after pleading guilty to one count of complicity to commit rape, two counts of permitting child abuse, one count of endangering children and one count of obstructing official business.
She will be eligible for parole in 20 years, and will have to register as a Tier 3 sec offender every 90 days – for the rest of her life.
In November, James John Kirksey was sentenced to two life terms in prison by the same judge.
Sentencing, Judge Frank Fregiato called the case a “crime against nature”.
He added: “If a 12-year-old girl cannot trust her mother to love and protect her, who in this world can she ever trust? She certainly wouldn’t expect her mother to be assisting in the rape.”