A police officer left a plastic bag filled with parts of a woman in her 80s at a garbage dump near a Tokyo police station in July, the Metropolitan Police Department said Friday, adding that some of them had yet to be recovered due to an error.

According to the MPD, the officer in question is in his 20s and was assigned to Mejiro Police Station. He was aware the bag contained human remains but discarded them because he thought they were unimportant due to their small size.

The bag was retrieved later from a garbage collector, but some of the remains were missing, the police said.

The woman was killed on July 26 after being hit by a train in Toshima Ward. The police are viewing the case as either an accident or a suicide.

The officer discarded the bag at the dump later in the day. When the police conducted an autopsy the following day, they realized some of her parts were missing. When the bag was retrieved on July 28, it was found to be ruptured.