Weston is also charged with kidnapping her niece, Beatrice Weston, 19, who disappeared as a child and was found last month by police. Investigators said Beatrice was starved, tortured, and occasionally locked in closets.
Also charged are Weston's boyfriend, Gregory Thomas, 47, her daughter, Jean McIntosh, 32, and Eddie Wright, 50.
Weston was convicted of third-degree murder in 1984 for the imprisonment-starvation death of 25-year-old Bernardo Ramos, who was originally thought to have died of natural causes.
Police also continue to probe the death of Donna Spadea, 59, who died in 2005 while in Weston's care in Philadelphia.
A medical examiner ruled that Spadea died of natural causes, but the case has been reopened because of the Weston connection, sources have said.
Authorities know of at least one other person who died under Weston's care: Maxine Lee, 39, from Philadelphia, who lived with Weston in Norfolk, Va.
Lee died in November 2008. A medical examiner attributed her death to meningitis - with severe malnutrition as a contributing factor - but police in Norfolk say they are reviewing the case in light of Weston's arrest.
Philadelphia Lt. Ray Evers would not comment on details of the investigation, but said detectives were pursuing many avenues in assembling a picture of Weston's life.
"They're looking at everything," he said.
Police believe Weston stole Social Security checks and other benefits from children and vulnerable adults for decades, collecting thousands of dollars per month, moving from state to state and operating under the radar of government agencies until several weeks ago.
Philadelphia Municipal Court President Judge Marsha H. Neifield on Wednesday granted a motion by Weston's attorney, George Yacoubian, to have her undergo a psychiatric evaluation. Neifield ordered the report to be completed by Nov. 16.
Weston has a long history of mental illness, according to court records. She has been diagnosed with schizophrenia and epilepsy.
Before her 1984 murder trial, Weston was initially deemed incompetent, but was eventually found fit to stand trial.
Contact staff writer Allison Steele at 215-854-2641 or firstname.lastname@example.org.
Staff writer Joseph A. Slobodzian contributed to this article.