The Suffolk County, Mass., district attorney called the case “one of the most complex, unusual and perplexing that this office has ever encountered.”

No charges will be filed against a 69-year-old woman after the bodies of four frozen infants were found  in a Boston apartment freezer in 2022, the Suffolk County district attorney announced this week.

District Attorney Kevin Hayden called the investigation into the circumstances of the grim discovery on Nov. 17, 2022, “one of the most complex, unusual and perplexing that this office has ever encountered.”

Investigators don’t know whether the four babies were born alive, which in part led to the decision not to bring criminal charges, Hayden said in a statement Tuesday.

The babies were found in a freezer in an apartment in South Boston after a man called police and said his wife found them while she was cleaning out the apartment of the man’s sister, the district attorney’s office said.