BERLIN (AP) — Berlin police say the U.S. Embassy has received another letter from a person who had previously sent threats and a white powder, which was later determined to be non-harmful.

Spokeswoman Valeska Jakubowski said police were investigating the letter, which was turned over to authorities Thursday after the embassy recognized the sender as the previous suspect from the other letters this summer. She says the current letter doesn't contain a threat so it doesn't appear a crime was committed.

She says the 54-year-old man behind all the letters was previously charged with disturbing the peace but his cases were thrown out because he was psychologically unfit for trial.

Explosive devices sent to high-profile political targets in the U.S. on Wednesday have put people on edge but Jakubowski says there's no link.