Sandra Pankow, Wisconsin, 1980

Sandra Pankow provided baby sitting in her home in Appleton, Wisconsin. 
Some babies were kept in a crib or playpen in the basement. Older 
children whom she watched testified that the infants sometimes were 
confined by sheets, blankets or boards placed over the crib or playpen 
and that when some babies cried, they were put in the basement with 
towels tied over their mouths. One baby died in 1980, and another in 
1982, apparently of sudden infant death syndrome (SIDS). When a third 
baby died in Pankow's home in 1985, the county coroner arranged for 
an autopsy. University pathologists tentatively determined the cause 
of death to be SIDS, but ultimately attributed the death to asphyxia. 
The bodies of the other two infants were exhumed. The pathologists 
concluded that these deaths also resulted from asphyxia. Pankow was 
charged with three second-degree murders, and a jury convicted her of 
two of them.

http://www.law.asu.edu/HomePages/Kaye/pubs/evid/clusters91JRSS.htm