True story - Brother in law ed 14 year old niece, should I intervene?

Yesterday, I visited my sister and her family. They were up in arms, because their 14 year old daughter was suspended from school along with a friend, for stealing $25 from another girls purse, and splitting the money. My brother in law took her to her room, and ed her, (over jeans according to my sister) with a leather belt. We could hear the whole thing. It sounded like 15-18 licks, and a lot of crying and begging to stop, and banished her to her room. My sister was ok with this, and I belive in preteens, but she is 14. Should I let them know how I feel, or is it there right as parents?