( CNN ) -- A 35-year-old father found to be sane when he killed his three young daughters last July was sentenced to three life sentences without the possibility of parole Monday . St. Croix County Judge Howard Cameron said the lives of sisters Amara,11 , Sophie , 8 , and Cecilia , 5 , were each so important that Aaron Schaffhausen had to serve each sentence consecutively . `` Each child has to be recognized as an individual girl , '' Cameron said . `` To make it concurrent would diminish what happened to those young girls . '' Schaffhausen and his wife Jessica had recently divorced when he came to spend the day with his daughters last year . According to the criminal complaint , Jessica -- who was not home at the time -- told police that two hours after Schaffhausen went to see the girls , he called her and said , `` You can come home now because I killed the kids . '' Jessica , who was in court Monday , was quiet throughout the proceedings . But her sister , Mary Elizabeth Stotz , called Schaffhausen an `` evil coward '' who `` should rot in hell '' during the victim impact statements . `` Aaron Schaffhausen , the man who helped genetically make those girls and shape them ... Aaron became the darkness , the boogeyman , and the monster under the bed , '' Stotz said . `` He was so evil that he took their unconditional love for him and used their love to lure them close enough so he could kill them . Their last memory is what an evil killer their dad was . '' Stotz also expressed fear that if Schaffhausen was allowed to be released on parole , he would get revenge on her family . Schaffhausen sat through the proceedings with no visible emotion , avoiding eye contact and almost inaudibly saying `` no '' when the judge asked him if he had anything to say . His attorney , John Kucinski , emphasized that his client suffered from a `` rare mental illness '' who committed a `` rare catathymic homicide . '' `` Nobody wins in this case , '' Kucinski said . `` Both families suffer , Jessica suffers , uncles , aunts . `` You can say , 'Three young girls are dead , we 've lost their lives , he did it because he hated Jessica , let 's get our revenge . ' Or you can try to actually take a look at mental illness and prevent things in the future , '' Kucinski said . A large photograph of the sisters stood by the judge , who finished his sentencing by saying , `` People in general , there is sometimes an evil , and there is goodness , '' Cameron said . The girls ' aunt remembered them as `` amazing people . ''
Aaron Schaffhausen killed his three daughters , ages 5 to 11 , last year . Judge : The three life sentences must be stacked , not served concurrently . Schaffhausen 's attorney says his client suffers from mental illness .