Susan Atkins aka Sadie Mae Glutz was a convicted murderer and member of the Charles Manson Family. Atkins was convicted of eight murders including that of actress Sharon Tate. Originally sentenced to death, her sentence was commuted in life in prison when the Supreme Court briefly overturned the death penalty. 
Atkins died of brain cancer on September 24, 2009.

Two page typed letter dated June 2001 and hand signed at the close, Susan. 

Includes the original mailing envelope with her complete return prison address in the upper left corner.

Susan Atkins Letter Signed with Envelope