LOS ANGELES (AP) _ A homeless cancer patient was charged Wednesday with mailing lethal cyanide packets disguised as nutritional supplements to people on her personal hit list.

Kathryn Schoonover, 50, could face up to 20 years in prison on each of two federal counts of using the mail to attempt to injure and kill. More charges were likely, lawyers said.

A federal affidavit accuses Ms. Schoonover of mailing cyanide packets to at least eight people, one of them a New York nurse who tasted the substance she thought was a vitamin supplement. She got an immediate, severe headache, according to police.

``The potential for many deaths was right there,'' Sheriff Sherman Block said Wednesday. ``It shows that there are so many ways anyone with an interest can create a mass tragedy in this country.''

There have been no known deaths from cyanide mailings.

Ms. Schoonover was arrested Sunday outside a Marina del Rey post office as she allegedly stuffed cyanide packets attached to health supplement brochures into 100 envelopes.

Four years ago, Ms. Schoonover spent several weeks at a psychiatric hospital in Albany, N.Y. At least two center employees received a package containing a health brochure and white powder but threw them away, federal postal inspector Joseph Taranto said in a court affidavit.

The names of the two employees were among those found on two hit lists found in Ms. Schoonover's van, Taranto said.

Taranto also said that since February, Ms. Schoonover had been under ``constant care'' as an outpatient at Los Angeles County-University of Southern California Medical Center.

For the past three years, Ms. Schoonover has been sending the Times Union of Albany copies of documents outlining alleged abuse at the psychiatric center. She claimed medications made her lose a baby, but medical officials told the newspaper that Ms. Schoonover was not pregnant.

The names of dozens of mental health professionals she encountered at the hospital were on her hit list, investigators said.