BOSTON (AP) — Letters written by Whitey Bulger provide a glimpse into the murderous Boston gang boss’ mundane life in prison and treatment by other inmates.

The letters being auctioned Sunday were provided by a man who says he became friends with Bulger when the geriatric gangster was briefly held at a federal prison in Brooklyn after being convicted in 2013 of participating in 11 murders.

Bulger was killed by fellow inmates last year shortly after being transferred to a troubled prison in West Virginia. Authorities have said two Massachusetts mobsters are under investigation for his killing but no one has been charged.

In the letters, Bulger wrote longingly about his days at Alcatraz and complained about how much his old neighborhood of South Boston has changed.