My neighbor is a level 3 sex offender. What law does the Sheriff have to keep harassing him?

Having a picnic and saw the sheriff drive up my neighbors driveway. They turned their siren and lights on and really made a disturbance. The two officers went up to the door and pounded very hard and we heard the house shake. They yelled they knew he was in there and if he refused to come out he would be arrested. They continued this till they saw us standing in our front door way then left. We saw the officers hands on their weapons at all times. My neighbor is a quiet guy and has been out of prison for 13 years, married and has kids. What laws does the Sheriff have to continue to harass this guy? Oh, my neighbor does not have any current complaints or charges on him. The way I look at it, the Sheriff is the terrorist and keeps on supporting this by their actions.