BOSTON (AP) — A Chelsea man already on the state’s sex offender registry is facing charges for allegedly taking lewd photos of a 6-year-old girl he knows.

George Shipps was arrested at his home Tuesday and charged in federal court with production of child pornography.

Authorities say they began investigating the 31-year-old Shipps last year and learned he had been exchanging child pornography images via email. After arresting him at his home, prosecutors say he told investigators that he took at least 10 pictures of a 6-year-old girl he knows in ‘‘various stages of undress’’ between August and September.

Prosecutors say Shipps is a Level 2 sex offender, considered a moderate risk to re-offend, for child enticement and child pornography possession charges.