An American woman has been handed an 80-year prison sentence for killing a Canadian mother and her daughter near Atlantic City.

U.S. media reports say a New Jersey superior court judge handed Antoinette Pelzer two consecutive 40 year sentences.

Pelzer had pleaded guilty in August to killing 80-year-old Po Lin Wan and her 47-year-old daughter Alice Mei See Leung in May 2012.

Surveillance video played for the court showed Pelzer running up stabbing the younger woman and then her mother when she tried to help.

According to a psychiatrist's report, Pelzer has denied robbery was a motive, but has not said why she stabbed the two Toronto women.

Court heard Pelzer was diagnosed with paranoid schizophrenia at age 24 and was not on her medication at the time of the killings.

The Philadelphia Inquirer reports that Pelzer apologized to the victims' family and told the court she was "real sick back then."