Stella Nickell, the women convicted of killing her husband and another woman by lacing pain capsules with cyanide, should be sentenced to life in prison for her conviction in the product tampering case, federal prosecutors say.

Nickell "has forfeited her right to walk among society for the remainder of her life," U.S. Attorney Gene Anderson and Assistant U.S. Attorney Joanne Maida said Wednesday in a three-page sentencing memorandum.

Nickell, 44, of suburban Auburn, Wash., was to be sentenced Friday on five federal product-tampering counts, including two stemming from the June 1986 deaths of her husband, Bruce Nickell, and Sue Snow, also of Auburn.