PHILADELPHIA -- Five people are accused of imprisoning disabled adults in a dank Philadelphia basement to steal their Social Security checks, a scheme that led to the murders of two of the victims, a federal prosecutor said on Wednesday.

Each defendant in the so-called Philadelphia dungeon case faces life in prison, U.S. Attorney Zane David Memeger said at a press conference to unveil the 196-count indictment.

The alleged ringleader, Linda Weston, 52, also could face the death penalty because she is charged with two counts of murder in aid of racketeering, Memeger said.

The indictment said her actions - chaining captives to a furnace, putting drugs in their food to subdue them and other means - had resulted in the death of two captives.

"The conduct here is shocking," Memeger said.

The indictment accuses the basement captors of racketeering to steal disability payments from adults with the mental capacity of a 10-year-old.

Memeger said the thefts amounted to $212,000 over 10 years.

Four of the defendants, including Weston and her daughter, had been charged with state crimes stemming from the scheme. A fifth, Nicklaus Woodward, of West Palm Beach, Fla., was arrested in Florida on Wednesday, Memeger said.

It is unclear, Memeger said, whether the original four will still face state as well as federal charges.

The malnourished captives were discovered in October 2011 by a landlord during a routine check of the two-story apartment house in the working class Tacony neighborhood. Authorities said two of those held had been imprisoned for roughly 11 years.